Danfoss ADAP-KOOL AK-PC 781 Design Manual Download

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AK-PC 781

Capacity

controller RS8GG602 © Danfoss 2015-03

Dynamic extension of the neutral zone

All refrigeration systems have a dynamic response time when

starting and stopping compressors. In order to avoid that the

controller will start/stop compressors shortly after each other, the

controller must be allowed some extra time after a compressor

start/stop to see the effect of the previous change in running

capacity.

In order to achieve this, a dynamic extension of the zones is

added.

The zones will be extended for a short period of time when

starting or stopping a compressor. By extending the zones the

PI controller will be slowed down in a short period of time after a

change in compressor capacity.

The amplitude of the zone extension depends upon the actual

running compressor capacity and upon the size of the compressor

step which is being stopped/started. The amplitude of the zone

extension is bigger when running with low compressor capacity

and when starting/stopping big compressor capacity steps.

However the time period for the zone extension is constant – after

a fixed time period after a compressor start/stop the dynamic

zone extension is reduced to 0.

Via the “Minimize number of couplings” setting it is possible to

influence how big the amplitude of the dynamic zone extension

should be in order to minimize the cycling of the compressors.

By setting “Minimize number of couplings” to “No reduction” there

will be no dynamic extension of the zones.

By setting “Minimize number of couplings” to “Low”, “Medium” or

“High” the dynamic extension of the zones will be activated. The

amplitude of the zone extension will be highest when “Minimize

number of couplings” is set to “High”. Please refer to the next

sketch which shows an example with 6 compressor steps and with

“Minimize number of couplings” set to “High”. Please also note that

the dynamic extension of the zones is highest at low compressor

capacity.

“Minimize number of couplings” = “High”

Actual band

As a consequence of the dynamic extension of the zones the

suction pressure might very well change zone for a period of

time when the controller is starting/stopping a compressor i.e.

the suction pressure is in the +Zone, but as the controller starts

a compressor, the zones are extended for a period of time and

during this period of time the suction pressure will be in the NZ.

In the controller the readout “Actual band” will show in which zone

the PI controller is operating – this includes the extension of the

zones.

The dynamic expansion of the neutral zone is not used when one

of the compressors in the group is speed-regulated.

Summary of Contents for ADAP-KOOL AK-PC 781

Page 1: ...Capacity controller with heat recovery function AK PC 781 Design Guide ADAP KOOL Refrigeration control systems ...

Page 2: ...f receiver pressure 66 Setup control of heat recovery 67 Setup Display 70 Setup Functions for General purpose 71 Separate thermostats 72 Separate pressostats 72 Separate voltage signals 73 Separate alarm inputs 73 Separate PI functions 74 Configuration of inputs and outputs 75 Set alarm priorities 77 Lock configuration 79 Check configuration 80 Check of connections 82 Check of settings 84 Schedule...

Page 3: ...e consumption peaks When the compressor does not start signals can be transmitted to other controllers so that the electronic expansion valves will be closed Regulation of liquid injection into suction line Start stop of liquid injection in heat exchanger cascade MT LT coordination between controllers in cascade control Safety monitoring of high pressure low pressure discharge temperature Capacity...

Page 4: ...ystems requirements are changed Flexible concept Controller series with common construction One principle many regulation uses modules are selected for the actual connection requirements The same modules are used from regulation to regulation Controller Top part Extension modules A regulation with few connections can be performed with the controller module alone If there are many connections one o...

Page 5: ...with few connections will give a setup with few settings A corresponding application with many connections will give a setup with many settings From the overview display there is access to further displays for the compressor regulation and the condenser regulation At the bottom of the display there is access to a number of general functions such as time table manual operation log function alarms a...

Page 6: ...formation display on the screen A corresponding display exists for all earlier alarms Here you can upload information if you need further details about the alarm history Trouble shooting The controller contains a function that continuously follows a number of measurements and deals with them The result indicates whether the function is OK or whether an error may be expected within a given period o...

Page 7: ...t with a specific software and by which input and output signals the relevant application will require If it is an application with few connections the controller module top part with belonging bottom part may be sufficient If it is an application with many connections it will be necessary to use the controller module plus one or more extension modules This section will give you a survey of possib...

Page 8: ... data communication is connected to other controllers in a big ger network Connection types There are various types of inputs and outputs One type may for example receive signals from sensors and switches another may receive a voltage signal and a third type may be outputs with relays etc The individual types are shown in the table below Optional connection When a regulation is planned set up it w...

Page 9: ...y for controller AK PS 150 36 VA AK PS 250 60 VA Accessories External display that can be connected to the controller module For showing say the suction pressure EKA 163B Display EKA 164B Display with operation buttons EKA 166 Display with operation buttons and LED for function cut in AK MMI Graphic display with operation Cable between display and controller Length 2 m 6 m Cable between graphic di...

Page 10: ...not be connected to the same output group Solid state outputs Can be used for loads that are cut in and out frequently e g Oil valves fans and AKV valves Max 240 V a c Min 48 V a c Max 0 5 A Leak 1 mA Max 1 AKV Stepper outputs Used for valves with stepper input 20 500 step s Separate supply to stepper outputs 24 a c d c 13 VA Ambient temperature During transport 40 to 70 C During operation 20 to 5...

Page 11: ...02 Danfoss 2015 03 11 Dimensions The module dimension is 72 mm Modules in the 100 series consist of one module Modules in the 200 series consist of two modules Controllers consist of three modules The length of an aggregate unit n x 72 8 ...

Page 12: ...troller is connected to a gateway type AKA 245 the controller s address must be set between 1 and 119 If it is a system manager AK SM then 1 999 Service PIN When the controller is connected to the data communication cable the gateway must have knowledge of the new controller This is obtained by pushing the key PIN The LED Status will flash when the gateway sends an acceptance message Operation The...

Page 13: ... at 1 1 AI 1 1 2 2 AI 2 3 4 3 AI 3 5 6 4 AI 4 7 8 5 AI 5 9 10 6 AI 6 11 12 7 AI 7 13 14 8 AI 8 19 20 9 AI 9 21 22 10 AI 10 23 24 11 AI 11 25 26 12 DO 1 31 32 13 DO 2 33 34 14 DO 3 35 36 15 DO 4 37 38 16 DO 5 39 40 41 17 DO6 42 43 44 18 DO7 45 46 47 19 DO8 48 49 50 24 25 Terminal 15 12 V Terminal 16 5 V Terminal 27 12 V Terminal 28 5 V Terminal 17 18 29 30 Cable screen Solid state outputs on 12 15 ...

Page 14: ... signals Supply voltage The supply voltage to the module comes from the previous mod ule in the row Supply voltage to a pressure transmitter can be taken from either the 5 V output or the 12 V output depending on transmitter type Light emitting diodes Only the two top LED s are used They indicate the following Voltage supply to the module Communication with the controller is active red error ...

Page 15: ...32 P0A P0B PcA PcB Paux Pgc Prec AKS 32R AKS 2050 1 xx bar AKS 32 1 zz bar U 0 5 V 0 10 V On Off Ext Main switch Day Night Door Level switch Active at Closed Open Point 5 6 7 8 Type AI5 AI6 AI7 AI8 Point 1 2 3 4 Type AI1 AI2 AI3 AI4 Terminal 9 12 V Terminal 10 5 V Terminal 15 5 V Terminal 16 12 V Terminal 11 12 13 14 Cable screen At the top the signal input is the left of the two terminals At the ...

Page 16: ... Function The module contains 8 inputs for on off voltage signals Signal AK XM 102A is for low voltage signals AK XM 102B is for high voltage signals Supply voltage The supply voltage to the module comes from the previous module in the row Light emitting diodes They indicate Voltage supply to the module Communication with the controller is active red error Status of the individual inputs 1 to 8 wh...

Page 17: ... 3 4 3 DI 3 5 6 4 DI 4 7 8 5 DI 5 9 10 6 DI 6 11 12 7 DI 7 13 14 8 DI 8 15 16 Point Signal Active at DI Ext Main switch Day Night Comp safety 1 Comp safety 2 Level switch Closed voltage on Open voltage off Point 5 6 7 8 Type DI5 DI6 DI7 DI8 Point 1 2 3 4 Type DI1 DI2 DI3 DI4 AK XM 102A Max 24 V AK XM 102B Max 230 V ...

Page 18: ...ule comes from the previous module in the row Supply voltage to a pressure transmitter can be taken from either the 5 V output or the 12 V output depending on transmitter type Galvanic isolation The inputs are galvanically separated from the outlets The outlets AO1 and AO2 are galvanically separated from AO3 and AO4 Light emitting diodes Only the two top LED s are used They indicate the following ...

Page 19: ...A P0B PcA PcB Paux Pgc Prec AKS 32R AKS 2050 1 xx bar AKS 32 1 zz bar U 0 5 V 0 10 V On Off Ext Main switch Day Night Door Level switch Active at Closed Open AO 0 10 V Terminal 9 12 V Terminal 10 5 V Terminal 11 12 Cable screen Galvanic isolation AI 1 4 AO 1 2 AO 3 4 Point 5 6 7 8 Type AO1 AO2 AO3 AO4 Point 1 2 3 4 Type AI1 AI2 AI3 AI4 3 Brown 2 Blue 1 Black 3 Brown 2 Black 1 Red At the top the si...

Page 20: ...l Light emitting diodes There are two rows with LED s They mean Left row Voltage supply to the controller Communication active with the bottom PC board red error Status of outputs DO1 to DO8 Right row AK XM 204B only Override of relays ON override OFF no override Fuses Behind the upper part there is a fuse for each output Keep the safety distance Low and high voltage must not be connected to the s...

Page 21: ... Module Point Terminal Active at 1 DO 1 25 27 2 DO 2 28 30 3 DO 3 31 33 4 DO 4 34 36 5 DO 5 37 39 6 DO 6 40 41 42 7 DO 7 43 44 45 8 DO 8 46 47 48 Signal Active at DO Comp 1 Comp 2 Fan 1 Alarm Solenoid valve On Off Point 1 2 3 4 5 6 7 8 Type DO1 DO2 DO3 DO4 DO5 DO6 DO7 DO8 ...

Page 22: ...tion Auto the controller carries out the control Light emitting diodes There are two rows with LED s They mean Left row Voltage supply to the controller Communication active with the bottom PC board red error Status of outputs DO1 to DO8 Right row AK XM 205B only Override of relays ON override OFF no override Fuses Behind the upper part there is a fuse for each output Keep the safety distance Low ...

Page 23: ...m 0 C S1 S2 Saux SsA SdA Shr Stw Sgc Pt 1000 P AKS 32R AKS 32 P0A P0B PcA PcB Paux Pgc Prec AKS 32R AKS 2050 1 xx bar AKS 32 1 zz bar U 0 5 V 0 10 V On Off Ext Main switch Day Night Door Level switch Active at Closed Open DO Comp 1 Comp 2 Fan 1 Alarm Light Rail heat Defrost Solenoid valve Active at on Off Terminal 9 12 V Terminal 10 5 V Terminal 21 12 V Terminal 22 5 V Terminal 11 12 23 24 Cable s...

Page 24: ...must be from a separate supply which must be galvanically separated from the supply for the control range 24 V d c 20 Power requirements 7 8 VA for controller 1 3 VA per valve A UPS may be necessary if the valves need to open close during a power failure Light emitting diodes There is one row with LED s It indicate the following Voltage supply to the module Communication active with the bottom PC ...

Page 25: ...40 ETS White Black Red Green CCM CCMT KVS 15 White Black Green Red KVS 42 54 CCM Valve Module Step Terminal 1 point 9 25 28 2 point 10 29 32 3 point 11 33 36 4 point 12 37 40 Point 1 2 3 4 5 6 7 8 Type AI1 AI2 AI3 AI4 AI5 AI6 AI7 AI8 Terminal 17 12 V Terminal 18 5 V Terminal 19 20 Cable screen Point 9 10 11 12 Step 1 2 3 4 Type AO ...

Page 26: ...he module contains two analog voltage outputs of 0 10 V Supply voltage The supply voltage to the module comes from the controller module Placing The module is placed on the PC board in the controller module Point The two outputs have points 24 and 25 They are shown on the earlier page where the controller is also mentioned Max load I 2 5 mA R 4 kohm ...

Page 27: ...mes for day night change over Fixed defrost times Saving of alarm log in case of power failure Saving of temperature log in case of power failure Connection The module is provided with plug connection Placing The module is placed on the PC board inside the top part Point No point for a clock module to be defined just connect it Working life of the battery The working life of the battery is several...

Page 28: ...nnected to either display output A B C and D Ex A P0 Suction pressure in C B Pc Condensing pressure in C When the controller starts up the display will show the output that is connected 1 output A 2 output B etc Placing The extension module can be placed at a distance of up to 15 m from the controller module Point No point has to be defined for a display module you simply con nect it EKA 163B EKA ...

Page 29: ...c from 100 V a c to 240 V a c Placing On DIN rail Effect Type Output tension Output current Power AK PS 075 24 V d c 0 75 A 18 VA AK PS 150 24 V d c adjustable 1 5 A 36 VA AK PS 250 24 V d c adjustable 2 5 A 60 VA Dimension Type High Width AK PS 075 90 mm 36 mm AK PS 150 90 mm 54 mm AK PS 250 90 mm 72 mm Connections AK PS 075 AK PS 150 AK PS 250 Supply to a controller ...

Page 30: ...DC should be connected to the communication module The 24 V can be sourced from the same supply that supplies the controller The supply for the communication module is galvani cally separated from the connected extension modules The terminals must not be earthed The power consumption is determined by the power consump tion of the total number of modules The controller strand load must not exceed 3...

Page 31: ...AK PC 781 Capacity controller RS8GG602 Danfoss 2015 03 31 ...

Page 32: ...ith a gateway a system manager or a clock module can be mounted in the controller Start stop of regulation Regulation can be started and stopped via the software External start stop can also be connected Warning The function stops all regulation including any high pressure regulation Excess pressure can lead to a loss of charge Start stop of compressors External start stop can be connected Alarm f...

Page 33: ...supply voltage is supplied from the module s terminal board where there is both a 5 V supply and a 12 V supply When programming the pressure trans mitter s pressure range must be set ON OFF voltage inputs DI This signal must be connected to two terminals The signal must have two levels either 0 V or voltage on the input There are two different extension modules for this signal type low voltage sig...

Page 34: ...r P0 S4 or Pctrl x PI regulation x Max number of compressor steps 8 Max number of unloaders each compressor 3 Identical compressor capacities x Different compressor capacities x Speed regulation of 1 or 2 compressors x Run time equalisation x Min restart time x Min On time x Liquid injection in suction line x Liquid injection in cascade heat exchanger x External start stop of compressors x Oil man...

Page 35: ...n the controller Heat recovery There are adjustment options for hot water and heat containers for heating The controller manages in order of priority 1 tap water 2 heating 3 gas cooler which removes the remaining excess heat Safety circuit If signals are to be received from one or more parts of a safety circuit each signal must be connected to an ON OFF input Day night signal for raising the sucti...

Page 36: ...re sensor Sc3 and Sgc Receivers Monitoring of CO2 level Control of pressure in oil receiver Controlling the tap water receiver temperature 55 C Controlling the receiver temperature for the heating circuit 40 C Data from this example is used on the next page The result is that the following modules should be used AK PC 781 controller AK XM 205A input and output module AK XM 208C stepper output modu...

Page 37: ...ck of suction pressure Separate alarm functions via DI 1 Load shedding Start of Heat recovery 1 1 Liquid level Oil level Pulse reset of oil management 9 On off outputs Compressors motors 4 Unloaders Fan motors circulation pumps 3 Alarm relay I m alive relay Inject ON Max 1 Separate thermostat and pressostat functions and voltage measure ments 1 Max 5 5 5 Heat recovery function via thermostat Max 1...

Page 38: ...nnection to the connected modules This status can be followed by the light emitting diode When the two catches for the DIN rail mounting are in open posi tion the module can be pushed into place on the DIN rail no matter where in the row the module is found Removal is likewise carried out with the two catches in the open position 8 9 Example continued Length If you use many extension modules the c...

Page 39: ...23 24 Closed Level switch oil comp 4 11 AI 11 25 26 Closed Solenoid valve oil comp 1 12 DO 1 31 32 ON Solenoid valve oil comp 2 13 DO 2 33 34 ON Solenoid valve oil comp 3 14 DO 3 35 36 ON Solenoid valve oil comp 4 15 DO 4 37 38 ON Solenoid valve oil Separator 16 DO 5 39 40 41 ON Circulation pump tw 17 DO6 42 43 44 ON Circulation pump hr 18 DO7 45 46 47 ON Room fan 19 DO8 48 49 50 ON Voltage signal...

Page 40: ...p gas cooler outlet Sgc 5 1 AI 1 1 2 Pt 1000 Temp by pased gas Shp 2 AI 2 3 4 Pt 1000 Start stop heat recovery tw 3 AI 3 5 6 Closed Gas cooler pressure Pgc 4 AI 4 7 8 AKS 2050 159 Speed control compressor 5 AO 1 9 10 0 10 V Speed control gas cooler fan 6 AO 2 11 12 0 10 V Speed control pump tw 7 AO 3 13 14 0 10 V Speed control pump hr 8 AO 4 15 16 0 10 V Connection diagram Drawings of the individu...

Page 41: ...AK PC 781 Capacity controller RS8GG602 Danfoss 2015 03 41 Example continued ...

Page 42: ...ated from the supply The and 24V input must not be earthed If using stepper motor valves the supply for these must be pro vided from a separate power supply For CO2 facilities it will also be necessary to safeguard the voltage to the controller and valves using UPS Power supply size The power consumption grows with the number of modules used Module Type Number á Effect Controller 1 x 8 8 VA Extens...

Page 43: ...ule 230 V 115 V to 24 V d c AK PS 075 18 VA Supply for controller 080Z0053 AK PS 150 36 VA 080Z0054 x AK PS 250 60 VA 080Z0055 Accessories External display that can be connected to the controller module For showing say the suction pressure EKA 163B Display 084B8574 EKA 164B Display with operation buttons 084B8575 EKA 166 Display with operation buttons and LED s 084B8578 AK MMI Graphic display with...

Page 44: ...44 Capacity controller RS8GG602 Danfoss 2015 03 AK PC 781 ...

Page 45: ... connected We have decided to work on the basis of the example we went through previously i e the following modules AK PC 781 controller module AK XM 205A input and output module AK XM 208C analog input module stepper output module AK XM 102B digital input module AK XM 103B analog input and output module AK OB 110 analog output module ...

Page 46: ...nected to voltage Press in the plate on the left hand side of the light emitting diodes and the plate on the right hand side for the red address changers Lift the top part off the basic module 2 Mount the extension module in the basic module 3 Put the top part back on the basic module The analog extension module will supply a signal to the ICMTS valve There are two outputs ...

Page 47: ... The basic module must not be connected to voltage Mounting and wiring continued When the two snap catches for the DIN rail mounting are in the open position the module can be pushed into place on the DIN rail regard less of where the module is on the row Disassembly is thus done with the two snap catches in the open posi tion In our example four extension modules are to be fitted to the basic mod...

Page 48: ...switch oil comp 4 11 AI 11 25 26 closed Solenoid valve oil Comp 1 12 DO 1 31 32 ON Solenoid valve oil Comp 2 13 DO 2 33 34 ON Solenoid valve oil Comp 3 14 DO 3 35 36 ON Solenoid valve oil Comp 4 15 DO 4 37 38 ON Solenoid valve oil Separator 16 DO 5 39 40 41 ON Circulation pump tw 17 DO6 42 43 44 ON Circulation pump hr 18 DO7 45 46 47 ON Room fan 19 DO8 48 49 50 ON Voltage signal to high pressure v...

Page 49: ...unting and wiring continued The screen on the pressure transmitter cables must only be connected at the end of the controller The supply voltage for the pressure transmitter should be taken from the same module that receives the pressure signal Warning Keep signal cables separate from cables with high voltage ...

Page 50: ...eady in just under one minute when the light emitting diode Status starts flashing slowly 5 When there is a network Set the address and activate the Service Pin 6 The controller is now ready to be configured Power Comm DO1 Status DO2 Service Tool DO3 LON DO4 I O extension DO5 Alarm DO6 DO7 DO8 Service Pin Internal communication between the modules Quick flash error Constantly On error Status on ou...

Page 51: ...on This section describes how the controller Is configured Is operated We have decided to work on the basis of the example we went through previously i e compressor control with 4 compressors and high pressure control using heat recovery and gas cooler The example is shown two pages in ...

Page 52: ...r an overview of it will always appear In case the overview is empty This is because the controller has not yet been set up The red alarm bell at the bottom right tells you that there is an active alarm in the controller In our case the alarm is due to the fact that the time in the controller has not yet been set For connecting and operating the AK service tool software please see the manual for t...

Page 53: ...pressor Common high pressure monitoring Po setting 15 C night displacement 5 K Oil management of each compressor High pressure control Gas cooler with speed controlled fans Pgc Max 100 bar High pressure control with signal from Sgc and Shp Pc regulates floating based on outdoor temperature sensor Sc3 Control of high pressure valve ICMTS Heat recovery for hot tap water Relay and 0 10 V Heat recover...

Page 54: ...r for the specific system and a corresponding access code for this person The controller will utilize the same language that is selected in the service tool but only if the controller contains this language If the language is not contained in the controller the settings and readings will be shown in English When the controller is supplied it has been set with standard authoriza tion for different ...

Page 55: ... 2 Select Lock Unlock configuration 3 Select Configuration lock Press the blue field with the text Locked 4 Select Unlocked Select Unlocked Configuration continued The controller can only be configured when it is unlocked The values can be changed when it is locked but only for those settings that do not affect the configuration ...

Page 56: ...he value of the required setting In the first field you enter a name for what the controller will be controlling The text written in this field can be viewed at the top of all screens together with the controller s address When the time is set the PC s time can be transferred to the controller When the controller is connected to a net work date and time will automatically be set by the system unit...

Page 57: ...on IT Compressor Parallel compressor there are special settings see the section on page 122 Heat recovery Heat recovery enabled To be adjusted later on Oil management Oil control enabled To be adjusted later on Quick setup A choice will give a number of predefined com binations which at the same time determine the connection points The display options depend on previous settings At the end of the ...

Page 58: ...ontrol or PWM digital scroll Control sensor Po Suction pressure Po is used for control S4 Media temperature S4 is used for control Pctrl Control pressure from the low pressure circuit for cascade Po refrigerant type Select refrigerant type P0 Refrigerant factors K1 K2 K3 Only used if Po refrigerant type is set to custom contact Danfoss for information Pctrl refrigerant type Select refrigerant type...

Page 59: ...e limit Po Any load below the limit value is freely permitted If the P0 exceeds the value a time delay is started If the time delay runs out the load limit is cancelled Override delay 1 Max time for capacity limit if P0 is too high Override delay 2 Max time for capacity limit if P0 is too high Kp Po 0 1 10 0 Amplifications factor for PI regulation Advanced control settings Select whether the advan...

Page 60: ...ssure in C If the limit is reduced the entire compressor capacity will be cutout P0 Max alarm Alarm limit for high suction pressure P0 P0 Max delay Time delay before alarm for high suction pressure P0 Safety restart time Common time delay before restarting the compressor Applicable to the functions Sd max limit Pc max limit and P0 min limit SH Min alarm Alarm limit for min superheat in suction lin...

Page 61: ...ontroller will reserve a safety relay for each compressor The relay terminal is connected in series to the compressor relay The relay can hereby stop the compressor if a lack of oil is registered when the compressor is force controlled Forced controlled to ON with the setting Manual or with the changeover on an extension module Danfoss recommends this function to avoid any compres sor damages due ...

Page 62: ...me time or whether each compressor is to be controlled separately Advanced stop Yes means pulses will be allowed following compressor stop Oil cycle pre delay Delay time before oil pulses commence Oil cycle post delay Delay time for signal that will stop oil pulses High oil alarm delay If an activation of the level switch is not registered before the time has expired an alarm will be given the com...

Page 63: ...t control mode for condenser Step Fans are step connected via relay outputs Step speed The fan capacity is controlled via a combination of speed control and step coupling Speed The fan capacity is controlled via speed control frequency converter Speed 1 step First fan speed controlled rest step coupling Fan speed type VSD and normal AC motors EC motor DC controlled fan motors VSD start speed Minim...

Page 64: ...quired of the condenser s air flow via an intelligent error detection method Monitoring requires the use of a Sc3 outer temperature sen sor which must be fitted by the condenser s air inlet FDD setting Set error detection function Tuning The controller makes an adjustment to the con denser concerned Note that tuning should only be done when the condenser is operating under normal operating conditi...

Page 65: ...the ICMTS valve s degree of closing Valve max OD Restriction of the ICMTS valve s degree of opening Pgc HR min Read the min acceptable pressure in the high pressure circuit during heat recovery Pgc HR offset Read the pressure increase during heat recovery Ramp down bar min Here you may select how quickly the reference must be changed after a completed heat recovery Temp at 100 bar Temperature at 1...

Page 66: ...re stopped with the External compressor stop function Prec min limit P band P band under Prec min where the ICMTS valve s degree of opening is increased Prec max limit P band P band over Prec max where the ICMTS valve s degree of opening is decreased Use hot gas dump Select whether hot gas should be supplied if the receiver pressure falls too low Prec hot gas dump Receiver pressure at which hot ga...

Page 67: ... is activated Heat recovery ramp down Configure how quickly the reference for the condenser pressure should be ramped down to normal level after heat recovery Configure in Kelvin per minute Heat recovery cutout Temperature value where the thermostat cuts out the heat recovery Heat recovery cutin Temperature value where the thermostat cuts out the heat recovery Heat recovery circuit applies only wh...

Page 68: ...stopped off Reference Here the required temperature of sensor Shr8 or Shr4 is set Thermostat band The permissible temperature variation around the reference Control signal Choose between Shr8 if regulation shall be done using only this sensor S4 S3 and a Delta T value if the controller shall regulate using this temperature difference until the Shr8 refer ence has been met Shr4 regulation is done u...

Page 69: ...t the displacement at which the fans shall fully stop Fan low limit Signal in at which throttling of the fans commences Fan high limit Signal in at which the fans are stopped BYPASS CONTROL V3gc bypass stop limit Signal in at which the gas cooler connects again after completed disconnect V3gc bypass start limit Signal in at which the gas cooler is disconnected Flowswitch delay Duration of stable s...

Page 70: ...used The setting is included here for information 3 Display setup Display The following can be read for the four outputs Comp control sensor P0 in temperature P0 i bar absolute Pctrl bar absolute S4 Ss Sd Cond control sensor Tc Pc bar absolute S7 Sgc Shp Pgc bar absolute Prec bar absolute Stw8 Shr8 Speed Compressor Unit readout Choose whether readings are to be in SI units C and bar or US units F ...

Page 71: ...number of required functions In our example we select one thermostat function for temperature control in the compressor room and one alarm function for monitoring the liquid level in the receiver The following number of different functions can be defined 5 thermostats 5 pressostats 5 voltage signal 10 alarm signals 3 PI regulations Configuration continued ...

Page 72: ...t has a separate outlet to control external automation For each thermostat adjust Name Which of the sensors is used Actual temp Temperature measurement on the sensor that is attached to the thermostat Actual state Actual status on the thermostat outlet Cut out temp Cut out value for the thermostat Cut in temp Cut in value for the thermostat High alarm limit High alarm limit Alarm delay high Time d...

Page 73: ...et can be used to monitor external volt age signals Each volt inlet has a separate outlet to control external automatic controls Set the number of general voltage inputs specify 1 5 Name Actual value read out of the measurement Actual state read out of outlet status Min readout State read out values at minimum voltage signal Max readout State read out values at maximum voltage signal Cutout Cut ou...

Page 74: ...hown in the display Reading the total reference Output Here you select the outlet function PWM pulse width modulated fx AKV valve Stepper signal for a step per motor or voltage signal Ref calc A Constant for variable value included in the refer ence Reference Ax B Ref calc B Fixed value included in reference Alarm mode Choose whether an alarm shall be attached to the function If it is set to ON al...

Page 75: ...t on this module each one of these has been connected to We furthermore select for each output whether the function is to be ac tive when the output is in pos Closed or Open Open has been selected here for all the safety circuits This means that the controller will receive signal under normal operation and register it as a fault if the signal is interrupted Load Output Module Point Active at Solen...

Page 76: ...x 1 3 Voltage input 1 5 0 5 V 0 10 V 1 5 V 2 10 V PI in temp PI ref temp PI in voltage PI in pres PI ref pres Function Output Module Point Type Voltage signal for high pressure valve ICMTS AO1 1 24 0 10 V Stepper signal for by pass valve CCM Step 1 3 9 CCM Speed control compressor AO1 5 5 0 10 V Speed control gas cooler fan AO2 5 6 0 10 V Speed control pump tw AO3 5 7 0 10 V Speed control pump hr ...

Page 77: ...t alarms that are current They will be shown with text in the three pictures All alarms that can occur can be set for a given order of priority High is the most important one Log only has lowest priority Disconnected gives no action The interdependence between setting and action can be seen in the table Setting Log Alarm relay selection Net work AKM dest Non High Low High High X X X X 1 Medium X X...

Page 78: ...8GG602 Danfoss 2015 03 AK PC 781 Press the button to go on to the next page 5 Set alarm priorities for thermostat and extra digital signals Configuration continued In our example we select the settings shown here in the display ...

Page 79: ...ke a comparison of selected func tions and define inputs and outputs The result can be seen in the next section where the setup is controlled Configuration continued Press in the field against Configuration lock Select Locked The setup of the controller has now been locked If you subsequently want to make any changes in the controller s setup remember first to unlock the configuration ...

Page 80: ...r that does not exist The selected point number on the selected mod ule had been set up for something different The error is corrected by setting up the output correctly Remember that the setup must be unlocked be fore you can change module and point numbers The settings are shown on a RED background If a setting has turned red you must control the setup again This may be due to the following The ...

Page 81: ...figuration of Analog Outputs Press the button to go on to the next page 6 Check configuration of Analog Inputs Configuration continued The setup of the analog outputs appears as it is supposed to according to the wiring made The setup of the analog inputs appears as it is supposed to according to the wiring made ...

Page 82: ... OFF MAN ON The output is forced to pos ON Before the control is started we check that all inputs and outputs have been connected as expected This controls requires that the setup is locked By means of the manual control of each output it can be checked whether the output has been correctly connected Cut out the safety circuit for compressor 1 Check that LED DI1 on the extension module module 2 go...

Page 83: ...Example of the connection between a defined output signal and a manual set value Check that all sensors show sensible values In our case we have no values This may be due to the following The sensor has not been connected The sensor is short circuited The point or module number has not been set up correctly The configuration is not locked Set Control of output voltage to manual Press in the Mode f...

Page 84: ...he pages the ones that can only be seen via the Scroll bar 4 Safety limits 5 Go back to the overview 6 Select condenser group Before the control starts we check that all the settings are as they should be The overview display will now show one line for each of the general functions Behind each icon there is a number of displays with the different settings It is all these settings that have to be c...

Page 85: ...can only be seen via the Scroll bar 8 Safety limits 9 Go back to the overview and Move on to the ther mostat group Check the settings 10 Go back to the overview and Move on to the press sostat group Check the settings 11 Go back to the overview and on to the general alarm inputs Check the settings 12 The controller setup has been completed Check of settings continued The last page contains safety ...

Page 86: ...schedule function for the night setback of the suction pressure In other cases where the controller is installed in a network with one system unit this setting may be made in the system unit which will then transmit a day night signal to the controller Press a weekday and set the time for the day period Continue with the other days A complete weekly sequence is shown in the display ...

Page 87: ...at 3 The arrow of the two other address switches must point at 0 2 Push the Service Pin Press down the service pin and keep it down until the Service Pin LED lights up 3 Wait for answer from the system unit Depending on the size of the network it may be up to one minute before the controller receives an answer as to whether it has been installed in the network When it has been installed the Status...

Page 88: ...list Press the red cross to remove cancelled alarms from the alarm list 5 Check active alarm again In our case we have a series of alarms We will tidy them up so that we only have those that are relevant In our case an active alarm remains because the control has stopped This alarm must be active when control has not started We are now ready for the startup of control Please note that active plant...

Page 89: ... bottom of the display 2 Start control First start of control continued Press in the field against Main switch Select ON The controller will now start controlling the compressors and the fans Note Control does not start until both the internal and external switch are ON Any external compressor stop breaker must be ON for the compressors to start ...

Page 90: ...pacity in percent Press in the blue field against Manual capacity If you need to manually adjust the capacity of the compressors you can use the following procedure WARNING If you force control the compressors the oil management will be shut down This could cause compressor damages If the wiring of the compressors includes safety relays monitoring will continue See Regulating functions Press the b...

Page 91: ...AK PC 781 Capacity controller RS8GG602 Danfoss 2015 03 91 5 Regulating functions This section describes how the different functions work ...

Page 92: ...the controller is to control an IT compressor for parallel compres sion the following regulation settings will be required The system type must be set to LT The regulation sensor must be set to Po the signal received from the receiver Prec Handling of sensor error Cap Ctrl Sensor P0 When P0 is used as the regulating sensor an error in the signal will mean that regulation continues with 50 cutin in...

Page 93: ...ction P0 optimisation is performed Here the override function will itself adapt the suction pressure to the max permissible If a short change in the suction pressure is needed for example up to 15 minutes in connection with defrosting the functions can be applied Here the PO optimisation will not have time to com pensate for the change Override with a 0 10 V signal When a voltage signal is connect...

Page 94: ... Integrator is looking at the deviation between the set point and the current pressure only and increases reduces the requested capacity correspondingly The amplification factor Kp on the other hand only looks at the temporary pressure changes In the Zone and Zone the controller will normally increase the requested capacity as the suction pressure is above the set point But if the suction pressure...

Page 95: ...number of couplings setting it is possible to influence how big the amplitude of the dynamic zone extension should be in order to minimize the cycling of the compressors By setting Minimize number of couplings to No reduction there will be no dynamic extension of the zones By setting Minimize number of couplings to Low Medium or High the dynamic extension of the zones will be activated The amplitu...

Page 96: ...ours will be started first At the different stops the compressor with the highest number of operating hours will be stopped first For compressors with several steps the operating time equalizing is carried out between the compressors main steps The left column shows the operating hours according to which the controller equalises The middle column shows as a percentage to what extent the individual...

Page 97: ...ombined with one step compres sors all compressors should be the same size 3 Speed regulated compressors can have different sizes in relation to subsequent compressors 4 When two speed regulated compressors are used they must have the same frequency range For cyclical coupling patterns the two speed regulated compressors should be the same size and the subsequent one step compressors should also b...

Page 98: ... is now up to the frequency converter to bring the speed up to Start speed The capacity step will now be cut in and the required capacity determined by the controller The start speed always ought to be set so high that a fast lubrication of the compressor is obtained during the start Controlling increasing capacity If the need for capacity becomes larger than Max Speed then the subsequent compress...

Page 99: ...following compressor steps If the variable part of the speed controlled compressor is smaller than the following compressors there will be holes in the capacity curve Example 1 speed controlled compressor with a nominal capacity at 50Hz of 20kw Variable speed range 25 50Hz 2 one step compressors of 20 kW Fixed capacity 25 HZ 50 HZ x 20 kW 10 kW Variable capacity 25 HZ 50Hz x 20 kW 10 kW The capaci...

Page 100: ... capacity has reached a value that allows the cut in of the next speed regulated compressor at start speed Afterwards both compressors will be cut in together and will run in parallel The following one step compressors will be cut in and out in accordance with the selected coupling pattern Controlling decreasing capacity The speed regulated compressors will always be the last compres sors running ...

Page 101: ...r will be started first then the first will be cut out and the second compressor will cut in Finally both compressors will be cut in together and will run in parallel The following one step compressors will in every case be handled in accordance with the best fit coupling pattern Example Two speed regulated compressors with a nominal capacity of 10 kW and 20 kW respectively Frequency range of 25 6...

Page 102: ...ital inlet The threshold value may not be set lower than the compressor s lowest capacity step Start speed When both load shedding signals are active the lowest limit value for the capacity will be the one that is applicable Max time A max period with low compressor capacity can be set When the period expires the system switches to normal regulation until the suction pressure is once again in plac...

Page 103: ...ops before T3 the release signal will drop out and thereby stop the LT compressors Example MT controller LT MT coordination MT compressor release MT controller uses an output MT compressor release which is activated when the first MT compressor starts LT controller LT MT coordination LT compressor release The LT controller uses an input LT compressor release which is con nected to the output signa...

Page 104: ...enerally though the MT circuit s suction pressure will also influence whether the release times for the LT circuit are met If the MT pressure is over the neutral zone LT must wait until the pressure drops into the neutral zone If the MT pressure is below the neutral zone the LT must start before MT starts MT release delay Here the output signal from the MT controller is delayed This means that the...

Page 105: ...orced closure signal via the relay switch is cancelled simultaneously with the first compressor being allowed to start The reason why the forced closure signal via the network is cancelled before the first compressor starts is that it will take some time to distribute the signal to all appliance controllers via the network with relay with data communication Here an injection signal from the LT con...

Page 106: ...s out Direct using an electrically operated expansion valve of the type AKV Four values are adjusted a start value for the Sd temperature min and max values for overheating and a period time for the AKV valve The pulse width modulating signal for the AKV valve shall be taken from one of the controller s four solid state outputs Time delay A time delay can be set which ensures that the injection is...

Page 107: ... and the reconnect value at 120 C Monitoring of min suction pressure P0 The function promptly cuts out all compressor steps if the suction pressure becomes lower than the permitted value The cutout limit can be defined in the range from 120 to 30 C The suction is measured with pressure transmitter P0 At cutout the alarm function is activated The alarm is cancelled and renewed cutin of compressor s...

Page 108: ...ressor that is shut down does not receive any oil When the compressor is in operation a signal from the compres sors oil level switch is expected When the signal is given the following process is carried out Adjustable delay time re started in case of chatter Oil injection commences after delay time sequence The solenoid valve follows the pulse process and the oil is injected Pulse time period tim...

Page 109: ...nput There is one reset and this applies to all com pressors Upon reset all the counters are reset It can also be reconnected via the service tool indicated in the Safety monitoring picture Simpel oil equalisation cyclical systems The function only begins when all compressors are in operation Here you can set an interval time at which the compressors will alternate in pausing for a given period of...

Page 110: ...Pc is used as the regulation sensor an error in the signal will result in condensator capacity being controlled as a function of the connected compressor capacity The compressor regulation will remain normal Cap Ctrl Sensor S7 If S7 is used as the regulation sensor an error in this sensor will result in further regulation that follows the Pc signal but in ac cordance with a reference that is 5K ov...

Page 111: ...d valve 2 Use of a thermostat for the function This function can be used with advantage where the heat recovery is used to warm up a water tank A temperature sensor is used to activate deactivate the heat recovery function When the temperature sensor becomes lower than the set cut in limit the heat recovery function is activated and the reference for the condenser temperature will be raised to a s...

Page 112: ...e capacity requirement becomes lower than the set minimum speed Start Min Speed regulation step regulation The controller starts the frequency converter and the first fan when the capacity requirement corresponds to the set starting speed The controller cuts in several fans step by step as the capacity requirement grows and then adapts the speed to the new situation The controller cuts out fans wh...

Page 113: ...nt has been run in and runs under normal operation conditions Capacity limitation during night operation The function is used to reduce the noise from the fans to a minimum It is primarily used in conjunction with a speed control but it will also be active when steps are cut in and out The setting is arranged as a percentage of the max capacity The limitation will be disregarded when safety functi...

Page 114: ...d 70 C depending on whether it is winter or summer If the Heat reclaim function is to raise the condensing pressure the temperature may increase to 90 or higher The Sc3 sensor should be positioned so that it measures the air intake temperature for the gas cooler If it measures a temperature that is too high the system s COP will become impaired The Sgc signal must be stable If this cannot be done ...

Page 115: ...ulation Here the pump must be controlled using variable speed When the Stw8 temperature has been achieved the gas is routed outside of the heat exchanger Stw8 and Stw8a Here regulation is done using the two tempera ture sensors in the receiver Stw8 is placed at the top and Stw8a further down The pump is controlled via on off and is connected when Stw8 is below the reference plus half the differenc...

Page 116: ...ntire recov ery circuit Sensors Shr2 Shr3 Shr4 and Shr8 Stw2 Sd All sensors must be installed due to safety reasons Shr2 The controller must know the temperature of the gas that is sent for condensation Shr3 Heat exchanger cold access Used for temperature regulation Shr4 Heat exchanger hot outlet Used for temperature regulation Shr8 Receiver temperature and in relation to the reference Stw2 or Sd ...

Page 117: ...the reference and heat recovery is carried out the condensation pressure may be increased The pressure is measured using the pressure transmitter Pgc and the controller at the valve Vhp How much the pressure shall be increased by is determined using a setting and an analogue voltage signal The signal must be a 0 10 V signal or a 0 5 V signal During heat recovery and a signal of 0 V the pressure is...

Page 118: ...00 capacity and will have the following impact a Control of the pump The pump is released to operation The valve is coupled up b Pressure increase The pressure is measured using the pressure transmitter Pgc and the controller at the valve Vhp If necessary the pressure will be kept at a value between Pgc HR min and Pg HR offset c Fan control The fan s capacity is tuned down so the temperature is in...

Page 119: ...cially developed for the pressure conditions that exist in a transcritical CO2 system The motor section of the valve is an ICAD actuator and is control led by a 0 10 V signal from the controller The valve s degree of opening can be restricted both at the clos ing point and in the entire open point The settings OD Min and OD max are adjusted as of the degree of opening and will restrict the voltage...

Page 120: ... activated by a signal from the heat recovery From ON at 0 Here the reference is changed to Pgc HR Min To ON at 100 Here the reference will increase further using the setting Pgc HR offset Between 0 and 100 the reference is variable Start up at a very low temperature It will be necessary to route the gas outside of the gas cooler if the gas temperature is too low Temperature limits are set under t...

Page 121: ...able to regulate the function but both are standard set to zero which makes the function inactive Receiver pressure s max limit Set a max receiver pressure If the controller register receiver pressure beyond the set value the ICMTS valve will be closed The opening degree will be linear through the p band so that the ICMTS valve will be closed by pressing set max receiver pressure plus set p band I...

Page 122: ...e desired level The compressor capacity will be vari able and the controller will emit a 0 10 V signal that indicates the desired capacity The function is activated by the MT controller which regularly records the opening degree of the Vrec valve When the opening degree is greater than the set value the MT controller will pull a relay This signal is recorded by the IT controller which starts the I...

Page 123: ...ct LT Select IT compressor From where the coordination with the MT controller is initiated DI input which receives signals when the IT compressor is to begin Relay output which emits signals when the compressor is running The Vrec valve s opening degree when the parallel compression is to start The start signal is first emitted when the opening degree is higher during the entire delay period The f...

Page 124: ...tput will be based on the actual pressure Alarm limits can be set for low and high pressure respectively including separate alarm delays The individual pressure control function can be adapted to the relevant application as it is possible to give the pressure control a name and indicate alarm texts General voltage input with ancillary relay 5 units 5 general voltage inputs are accessible for monit...

Page 125: ...ng might be Check max and min settings Increase the integration time so that it is not mixed up with the balancing Reduce Kp to start with Start the process Adjust Kp until the process starts fluctuating and is constantly fluctuating Adjust Kp to half the value Adjust Tn down until the process starts fluctuating again Adjust Tn to double values Settings Variable reference part Input ref select It ...

Page 126: ...rrect sensor must be in order for 10 minutes before the sensor alarm deactivates Sensor calibration The input signal from all connected sensors can be corrected A correction will only be necessary if the sensor cable is long and has a small cross sectional area All displays and functions will reflect the corrected value Clock function The controller contains a clock function The clock function is ...

Page 127: ...quently read the historical values in the form of graph presentations The log only works when the clock has been set Forced operation via network The controller contains settings that can be operated from the gateway s forced operation function via data communication When the forced operation function asks about one change all the connected controllers on this network will be set simultaneously Th...

Page 128: ...apacity x x o62 Select of predefined configuration This setting will give a selection of predefined combina tions which at the same time establish the connections points At the end of the manual an overview of options and connection points is shown After the configuration of this function the controller will shut down and restart x x x o93 Lock of configuration It is only possible to select a pred...

Page 129: ...ep Rate The desired valve drive rate in steps per second This value is limited to 20 500 steps sec Holding Current The percent of the programmed Max Phase Current that should be applied to each phase of the stepper output when the valve is stationary If required this current ensures that the valve main tains its last programmed position This value is limited to a range of 0 70 given in 10 steps Ov...

Page 130: ... via few compressors Preconditions for using this compressor application are All compressors are the same size The capacity regulated compressor can have up to three unload valves The main step and the unload valves can be different sizes i e 50 25 and 25 This compressor combination can be handled in the following coupling patterns Cyclical General regarding Handling Cutin The capacity regulated c...

Page 131: ...d to fill capacity gaps Operating hours are equalised between the one step compres sors 3 and 4 Compressor application 4 Only capacity controlled compres sors The controller is capable of controlling capacity regulated piston compressors of the same size with up to 3 unload valves Preconditions for using this compressor application are All compressors are the same size The capacity regulated compr...

Page 132: ...n capacity Decreasing capacity The small one step compressor is cut out when the speed regu lated compressor has reached minimum speed 30 Hz When the speed regulated compressor again reaches minimum speed 30 Hz the smallest one step compressor C2 is cut out and the big one step compressor C3 is cut in When the speed regulated compressor again reaches min speed 30 Hz the large one step compressor C...

Page 133: ...of coupling pattern The same frequency band for both speed regulated compressors One step compressors of the same or different sizes depending on the choice of coupling pattern This compressor combination can be handled in accordance with the following coupling patterns Cyclical Best fit Handling the speed regulated compressor For more information on the general handling of the speed regu lated co...

Page 134: ...Example 2 In this example the speed regulated compressors are of different sizes and the following one step compressors are also of different sizes Increasing capacity The smallest speed regulated compressor C1 starts when the desired capacity equals the start speed When the smallest speed regulated compressor C1 has reached max speed 90 Hz the large speed regulated com pressor C2 cuts in and the ...

Page 135: ...AK PC 781 Capacity controller RS8GG602 Danfoss 2015 03 135 ...

Page 136: ...cuit is defective Saux_ sensor error Signal from extra Temp sensor Saux_ is defective Paux_ sensor error Signal from extra pressure sensor Paux_ is defective All compressors Common safety High Common compr Safety cutout All compressors have been cut out on common safety input Comp 1 safety Comp 2 safety Comp 3 safety _________________ Comp 12 safety Medium Comp X oil pressure cut out Compressor no...

Page 137: ...t is too high Receiver alarm High Prec Alarm from the receiver External power loss High External power loss Supply is interrupted A message alert All other alarms stopped Steppervalve High Stepper Vhp Vrec PI Vliq Open coil Shorted output Error Power failure Check the supply to the current valve In the event of an error or power failure check the supply to the stepper module System alarms The alar...

Page 138: ... AK XM 205A Oil lvl comp 1 Oil lvl comp 2 Oil lvl comp 3 Oil Low Separ 1 Oil Hi Separ 1 Modul 6 AK XM 205A Saux 1 2b MT 1 vsd comp 2 single vsd fans Boost Gas cooler Receiver TW HR Modul 1 Controller MT Comp Request Loadshed 1 Loadshed 2 Sgc Shp Main Sw Modul 2 AK XM 102B Comp 1 safety Comp 2 safety Comp 3 safety VSD C 1 safety Fan 1 safety Modul 3 AK XM 103A Volt input 1 Power loss Vhp ICMTS Modu...

Page 139: ...peed Fan 2 safety VSD cond safety Speed tw Speed hr HR Shr4 HR Shr8 Vrec CCM GasCool Pgc Receiver Prec HR tw V3tw HR tw Pump tw HR V3hr HR pump hr GasCool V3gc Thermost 1 2ab Sc3 Sd Ss P0 Pc Comp 1 Comp 2 Comp 3 Liq Inject suction Fan 1 Fan 2 Alarm MT Comp Release Comp speed Fan speed Fan 2 safety VSD cond safety Speed tw Speed hr HR Shr4 HR Shr8 Vrec CCM Volt input 1 Poil rec Oil Valve C1 Oil Val...

Page 140: ...ight Heat recovery Main Sw Modul 2 AK XM 102B Comp 1 safety Comp 2 safety Comp 3 safety Comp 4 safety Comp 5 safety Modul 3 AK XM 205A 14 MT 6 single 6 fan HFC Cascade HR Modul 1 Controller MT Comp Request Loadshed 1 Loadshed 2 Night Heat recovery Main Sw Modul 2 AK XM 102B Comp 1 safety Comp 2 safety Comp 3 safety Comp 4 safety Comp 5 safety Comp 6 safety Modul 3 AK XM 204A Fan 1 Fan 2 Fan 3 Fan ...

Page 141: ...an 1 Fan 2 Fan 3 Fan 4 Volt input 1 Saux 1 MT Comp Release Liq Inject Heat Ex Thermost 1 Heat recovery 13 Sc3 Sd Ss P0 Pc Comp 1 Comp 2 Comp 3 Comp 4 Comp 5 Fan 1 Fan 2 Fan 3 Fan speed Volt input 1 Saux 1 Fan 4 Fan 5 Fan 6 MT Comp Release Liq Inject Heat Ex Thermost 1 Heat recovery 14 Sc3 Sd Ss P0 Pc Comp 1 Comp 2 Comp 3 Comp 4 Comp 5 Comp 6 Alarm MT Comp Release Liq Inject Heat Ex Heat recovery 1...

Page 142: ...allation or site conditions can give rise to malfunctions of the control system and ultimately lead to a plant breakdown Every possible safeguard is incorporated into our products to prevent this However a wrong installation for example could still present problems Electronic controls are no substitute for normal good engineering practice Danfoss will not be responsible for any goods or plant comp...

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