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6-1

Chapter 6

Bath Use

READ BEFORE PLACING THE BATH IN SERVICE

The information in this section is for general information only. It is not designed to

be the basis for calibration laboratory procedures. Each laboratory will need to

write their own specific procedures.

6.1 General

Be sure to select the correct fluid for the temperature range of the calibration.

Bath fluids should be selected to operate safely with adequate thermal properties

to meet the application requirements. Also, be aware that some fluids expand

and could overflow the bath if not watched. Refer to General Operation, section

8, for information specific to fluid selection and to the MSDS sheet specific to the

fluid selected. Generally, baths are set to one temperature and used to calibrate

probes only at that single temperature. This means that the type of bath fluid

does not have to change. Additionally, the bath can be left energized reducing

the stress on the system.
The bath generates extreme temperatures. Precautions must be taken to prevent

personal injury or damage to objects. Probes may be extremely hot or cold when

removed from the bath. Cautiously handle probes to prevent personal injury.

Carefully place probes on a heat/cold resistant surface or rack until they are at

room temperature. It is advisable to wipe the probe with a clean soft cloth or

paper towel before inserting it into another bath. This prevents the mixing of

fluids from one bath to another. If the probe has been calibrated in liquid salt,

carefully wash the probe in warm water and dry completely before transferring it

to another fluid. Always be sure that the probe is completely dry before inserting

it into a hot fluid. Some of the high temperature fluids react violently to water or

other liquid mediums. Be aware that cleaning the probe can be dangerous if the

probe has not cooled to room temperature. Additionally, high temperature fluids

may ignite the paper towels if the probe has not been cooled.
For optimum accuracy and stability, allow the bath adequate stabilization time

after reaching the set-point temperature.

Содержание 7008

Страница 1: ...reserved Specifications are subject to change without notice All product names are trademarks of their respective companies 7008 Calibration Bath Users Guide Via Acquanera 29 22100 Como tel 031 526 566 r a fax 031 507 984 info calpower it www calpower it ...

Страница 2: ...rvice center to obtain return authorization information then send the product to that service center with a description of the difficulty postage and insurance prepaid FOB Destination Fluke assumes no risk for damage in transit Following warranty repair the product will be returned to Buyer transportation prepaid FOB Destination If Fluke determines that failure was caused by neglect misuse contami...

Страница 3: ...oduction 2 1 3 Specifications and Environmental Conditions 3 1 Specifications and Environmental Conditions 3 1 3 1 Specifications 3 1 3 2 Environmental Conditions 3 1 4 Quick Start 4 1 Quick Start 4 1 4 1 Unpacking 4 1 4 2 Set Up 4 1 4 3 Power 4 2 4 4 Setting the Temperature 4 2 5 Installation 5 1 Installation 5 1 5 1 Bath Environment 5 1 5 2 Dry out Period 5 1 5 3 Bath Preparation and Filling 5 2...

Страница 4: ... 1 8 Safety 8 2 8 1 9 Cost 8 3 8 1 10 Commonly Used Fluids 8 3 8 1 11 Fluid Characteristics Chart 8 4 8 2 Stirring 8 7 8 3 Power 8 7 8 4 Heater 8 7 8 5 Cooling 8 7 8 6 Temperature Controller 8 8 9 Controller Operation 9 1 Controller Operation 9 1 9 1 Bath Temperature 9 1 9 2 Reset Cut out 9 1 9 3 Temperature Set point 9 3 9 3 1 Programmable Set points 9 3 9 3 2 Set point Value 9 4 9 3 3 Set point ...

Страница 5: ...tion 10 3 10 2 IEEE 488 Communication optional 10 3 10 2 1 Setup 10 3 10 2 1 1 IEEE 488 Interface Address 10 6 10 2 2 IEEE 488 Operation 10 6 10 3 Interface Commands 10 6 10 4 Power Control Functions 10 7 10 4 1 Heater Control 10 7 10 4 2 Cooling Control 10 7 11 Calibration Procedure 11 1 Calibration Procedure 11 1 11 1 Calibration Points 11 1 11 2 Measuring the Set point Error 11 1 11 3 Computing...

Страница 6: ...7008 Users Guide iv ...

Страница 7: ...tional Electrical Symbols 1 1 2 Specifications 3 1 3 Table of Various Fluid Characteristics 8 5 4 Proportional Band Fluid Table 9 8 5 Interface Command Summary 10 4 6 Serial Power Control Functions 10 8 7 Temperature Range Control Functions 10 8 ...

Страница 8: ...7008 Users Guide vi ...

Страница 9: ...ontrols Side Panel 7 2 4 Back Panel 7 4 5 Lid Options and Drain View 7 5 6 Chart of Various Fluid Characteristics 8 6 7 Controller Operation Flowchart 9 2 8 Bath temperature fluctuation at various proportional band settings 9 7 9 Serial cable wiring 10 2 10 Sample calibration computations 11 3 ...

Страница 10: ...7008 Users Guide viii ...

Страница 11: ...symbols may be used on the instrument or in this manual Table 1 International Electrical Symbols Symbol Description AC Alternating Current AC DC Battery Complies with European Union directives DC Double Insulated Electric Shock Fuse PE Ground Hot Surface Burn Hazard Read the User s Manual Important Information O Off I On ...

Страница 12: ...identifies conditions and actions that may pose hazards to the user CAUTION identifies conditions and actions that may damage the instrument being used 1 2 1 Warnings WARNINGS To avoid possible electrical shock or personal injury follow these guidelines GENERAL DO NOT use the instrument for any application other than calibration work The instrument was designed for temperature calibration Any othe...

Страница 13: ...ompressor it may require two people to safely move the bath The area containing the compressor will be heavier than the rest of the bath DO NOT move a bath filled with fluid BURN HAZARD Extremely cold temperatures may be present in this equipment Freezer burns and frostbite may result if personnel fail to observe safety precautions High temperatures may be present in this equipment Fires and sever...

Страница 14: ...ection 9 8 Cutout 1 2 2 Cautions CAUTIONS Always operate this instrument at room temperature between 41 F and 122 F 5 C to 50 C Allow sufficient air circulation by leaving at least 6 inches 15 cm of clearance around the instrument DO NOT overfill the bath Overflowing fluid may damage the electrical system See Section 5 3 Bath Preparation and Filling for specific instructions Read Section 6 Bath Us...

Страница 15: ...is energized or when it is moved from one location to another Turning the bath ON or OFF does not trigger the delay If a High Low voltage condition exists for longer than 5 seconds the bath de energizes An amber indicator on the back panel lights when this condition exists Re energization is automatic upon correction of the fault condition and after a delay cycle of about 2 minutes If a fault cond...

Страница 16: ...e 86 10 6 512 3436 Telefax 86 10 6 512 3437 E mail xingye han fluke com cn Fluke South East Asia Pte Ltd Fluke ASEAN Regional Office Service Center 60 Alexandra Terrace 03 16 The Comtech Lobby D 118502 SINGAPORE Phone 65 6799 5588 Telefax 65 6799 5588 E mail antng singa fluke com When contacting these Service Centers for support please have the following information available Model Number Serial N...

Страница 17: ...The controller uses a microcontroller to execute the many operating functions User interface is provided by the 8 digit LED display and four key switches Digital remote communications is optionally available with a RS 232 or IEEE 488 interface The tank for the 7008 is stainless steel The 7008 holds 44 liters There are two lids available the standard lid with a rectangular access hole and an option...

Страница 18: ...7008 Users Guide 2 2 Figure 1 Bath Assembly ...

Страница 19: ...ng capacity 100 200 watt Refrigeration 1 5 Hp Heaters 500 and 1000 watt Power 115 V AC 10 60 Hz 15 A 1290 W 230 V AC 10 50 Hz 8 A 1290 W optional 230 V AC 10 60 Hz 8 A 1400 W optional NOTE If voltage is outside the 10 the compressor may be damaged 230 V models are frequency specific System fuse 115 V 15 A 250 V SB 230 V 8 A 250 V SB Heater fuse 115 V 10 A 250 V FB 230 V 6 A 250 V FB Exterior dimen...

Страница 20: ...nce and cleaning recommendations can be found in the Maintenance Section of this manual The instrument operates safely under the following conditions temperature range 5 to 50 C 41 to 122 F ambient relative humidity maximum 80 for temperature 31 C decreasing linearly to 50 at 40 C pressure 75kPa 106kPa mains voltage within 10 of nominal vibrations in the calibration environment should be minimized...

Страница 21: ...hat may have occurred during shipment If there is shipping damage notify the carrier immediately Verify that all components are present 7008 bath Access cover Thermometer fill hole cover Drain valve with brass elbow Controller probe Report of test User s guide Resistor rack If you are missing any item please contact an Authorized Service Center for assistance See Section1 3 for Service Center cont...

Страница 22: ...each the previously programmed temperature set point The front panel LED display will indicate the actual bath temperature 4 4 Setting the Temperature In the following discussion a button icon with the word SET UP EXIT or DOWN indicates the panel button while the dotted box indicates the display reading Explanation of the button or display reading is to the right of each button or display value To...

Страница 23: ...switch to position HIGH to allow the bath to more quickly reach a higher temperature The HIGH setting may be necessary to reach higher temperatures and control at high temperatures When setting the set point temperature is careful not to exceed the temperature limit of the bath fluid The over temperature cut out should be correctly set to prevent this from happening See Section 9 8 If operating th...

Страница 24: ...7008 Users Guide 4 4 ...

Страница 25: ...g injury or if the bath and cart tip the fluid could cause damage to the surrounding area and personal injury to personnel If the bath must be moved be sure to drain the fluid to prevent any injury The side of the bath with the compressor is heavier than the tank side To safely move the bath two people are required 5 1 Bath Environment The Model 7008 Bath is a precision instrument which should be ...

Страница 26: ...ature rises to prevent overflow or splashing Remove excess fluid if necessary and with caution if the fluid is hot Be careful to prevent bath fluid from spilling on the stirring motor while filling Note that under filling may reduce bath performance and may possibly damage the bath heater 5 4 Probe Inspect the bath controller probe It should not be bent or damaged in any way Reasonable caution sho...

Страница 27: ...stem The bath generates extreme temperatures Precautions must be taken to prevent personal injury or damage to objects Probes may be extremely hot or cold when removed from the bath Cautiously handle probes to prevent personal injury Carefully place probes on a heat cold resistant surface or rack until they are at room temperature It is advisable to wipe the probe with a clean soft cloth or paper ...

Страница 28: ... get too warm during calibration at high temperatures a heat shield could be used just below the probe handle This heat shield could be as simple as aluminum foil slid over the probe before inserting it in the bath or as complicated as a specially designed reflective metal apparatus When calibrating over a wide temperature range better results can generally be achieved by starting at the highest t...

Страница 29: ...t the bath temperature set point access and set other operating parameters and access and set bath calibration parameters A brief description of the functions of the buttons follows SET Used to display the next parameter in a menu and to set parameters to the displayed value DOWN Used to decrement the displayed value of settable parameters UP Used to increment the displayed value EXIT Used to exit...

Страница 30: ...1 the BACK PRESSURE valve 2 the COOLING TEMPERATURE regulating valve and 3 the COOLING TEMP gauge With the interface option an extra cooling valve HIGH is provided Figure 3 Refrigeration Controls Side Panel 1 The BACK PRESSURE valve adjustment is used to control the amount of cooling supplied to the system This valve reduces the cooling capacity by restricting the flow of refrigerant to the bath a...

Страница 31: ...ng Pressure above 90 PSIG 3 The COOLING TEMP gauge is used to indicate the temperature at which the refrigerant is evaporating The COOLING TEMP regulating valve is used to set and then controls this temperature 7 3 Back Panel The back panel has six standard features and two optional features See Figure 4 The standard features are 1 the probe connector 2 the stirrer power outlet 3 the system and he...

Страница 32: ... RS 232 8 If the bath is supplied with a GPIB IEEE 488 interface the interface cable attaches to the back of the bath at the connector labeled IEEE 488 9 The Mains out of Range indicator shows when the AC mains are out of range for the instrument to operate WARNING Extreme caution must be maintained to prevent harm to the user or the surrounding environment Do not exceed a 120 C fluid temperature ...

Страница 33: ...They all have the same overall dimensions but the optional lid see Figure 5 has a recirculation pump and the standard lid has a stirring motor with rectangular access hole Their features are described with reference to figure numbers as follows Figure 5 Lid Options and Drain View ...

Страница 34: ...his hole must be covered to prevent thermal disturbance to the bath Covers may be purchased separately from Hart Scientific 4 The circulation inlet outlet is the access area or the inlet and outlet for the circulation pump 5 The stirrer pump motor is mounted on the bath tank lid It drives the stirring propellers to provide mixing of the bath fluid Proper mixing of the fluid is important for good c...

Страница 35: ...gher temperatures may affect temperature stability because of cool condensed fluid dripping into the bath from the lid The bath temperature should be limited by setting the safety cut out so that the bath temperature cannot exceed the safe operating temperature limit of the fluid 8 1 2 Viscosity Viscosity is a measure of the thickness of a fluid how easily it can be poured and mixed Viscosity affe...

Страница 36: ...ease in fluid volume as the bath temperature changes may cause overflow Excessive thermal expansion may also be undesirable in applications where constant liquid level is important Oils typically have significant thermal expansion 8 1 6 Electrical Resistivity Electrical resistivity describes how well the fluid insulates against the flow of electric current In some applications such as measuring th...

Страница 37: ...per gallon for synthetic oils Cost may be an important consideration when choosing a fluid 8 1 10 Commonly Used Fluids Below is a description of some of the more commonly used fluids and their characteristics 8 1 10 1 Water Water is often used because of its very low cost availability and excellent temperature control characteristics Water has very low viscosity and good thermal conductivity and h...

Страница 38: ...as well For information on silicone oils contact Hart Scientific 8 1 11 Fluid Characteristics Chart Table 3 and Figure 6 have been created to provide help in selecting a heat ex change fluid media for your constant temperature bath The charts provide both a visual and numerical representation of most of the physical qualities important in making a selection The list is not all inclusive many usabl...

Страница 39: ...iling point and others may be shown Freezing Point The freezing point of a fluid is an obvious limitation to stirring As the freezing point is approached high viscosity may also limit good stirring Table 3 Table of Various Fluid Characteristics Pour Point The pour point represents a handling limit for the fluid Viscosity Points shown are at 50 and 10 centistokes Greater than 50 centi stokes stirri...

Страница 40: ...s Fluid Characteristics Flash Point The flash point is the point at which ignition may occur See flash point discussion in Section 8 1 8 The point shown may be either the open or closed cup flash point Boiling Point At the boiling point of the fluid the temperature stability is difficult to maintain Fuming is excessive Excessive amounts of heater power may be required because of the heat of vapori...

Страница 41: ... indicates the controller hardware configuration This data is used in some circumstances for diagnostic purposes 8 4 Heater The power to the bath heater is precisely controlled by the temperature controller to maintain a constant bath temperature Power is controlled by periodically switching the heater on for a certain amount of time using a solid state relay The front panel red green control indi...

Страница 42: ...nically compared with the programmable reference signal amplified and then fed to a pulse width modulator circuit which controls the amount of power applied to the bath heater The bath is operable within the temperature range given in the specifications For protection against solid state relay failure or other circuit failure the microcontroller will automatically turn off the heater with a second...

Страница 43: ...libration parameters Operation is summarized in Figure 7 9 1 Bath Temperature The digital LED display on the front panel allows direct viewing of the actual bath temperature This temperature value is what is normally shown on the display The units C or F of the temperature value are displayed at the right For example 25 00 C Bath temperature in degrees Celsius The temperature display function may ...

Страница 44: ...mperature is lowered below the cut out set point With manual reset mode the cut out must be reset by the operator after the temperature falls below the set point When the cut out is active and the cut out mode is set to manual reset then the display will flash cut out until the user resets the cut out To access the reset cut out function press the SET button Access cut out reset function The displ...

Страница 45: ...Controller Operation 9 2 Reset Cut out 9 9 3 Figure 7 Controller Operation Flowchart ...

Страница 46: ...erature should also be set below the upper limit of the fluid Setting the bath temperature involves three steps 1 select the set point memory 2 adjust the set point value and 3 adjust the vernier if desired 9 3 1 Programmable Set points The controller stores 8 set point temperatures in memory The set points can be quickly recalled to conveniently set the bath to a previously programmed temperature...

Страница 47: ... The user may want to adjust the set point slightly to achieve a precise bath temperature The set point vernier allows one to adjust the temperature below or above the set point by a small amount with very high resolution Each of the 8 stored set points has an associated vernier setting The vernier is accessed from the set point by pressing SET The vernier setting is displayed as a 6 digit number ...

Страница 48: ...adjustment function by pressing SET From the temperature display function accesses the unit s selection by pressing SET 4 times 25 00 C Bath temperature Access set point memory 1 25 0 Set point memory Access set point value C 40 00 Set point value Access vernier 0 00000 Vernier setting Access scale units selection Un C Scale units currently selected Press UP or DOWN to change the units Un F New un...

Страница 49: ... in the secondary menu Press SET and EXIT simultaneously and release The heater power will be displayed as a percentage of full power Access heater power in secondary menu 12 Pct Heater power in percent To exit out of the secondary menu press EXIT To continue on to the proportional band setting function press SET 9 7 Proportional Band In a proportional controller such as this the heater output pow...

Страница 50: ...re heater power setting and fluid viscosity The proportional band should be wider when the higher power setting is used so that the change in output power per change in temperature remains the same The proportional band should also be wider when the fluid viscosity is higher because of the increased response time The proportional band width is easily adjusted from the bath front panel The width ma...

Страница 51: ...portional band adjustment may be accessed within the secondary menu Press SET and EXIT to enter the secondary menu and show the heater power Then press SET to access the proportional band Access heater power in secondary menu 12 Pct Heater power in percent Access proportional band Pb 0 101C Proportional band setting To change the proportional band press UP or DOWN Pb 0 060C New proportional band s...

Страница 52: ...ter will be shut off and the bath will cool The bath will cool until it reaches a few degrees below the cut out set point temperature At this point the action of the cut out is determined by the setting of the cut out mode parameter The cut out has two selectable modes automatic reset or manual reset If the mode is set to automatic then the cut out will automatically reset itself when the bath tem...

Страница 53: ...meters menu Press SET to enter the menu The probe parameters menu contains the parameters DO and DG which characterize the transfer function of the linearized thermistor control probe These parameters may be adjusted to improve the accuracy of the bath This procedure is explained in detail in Section 11 The probe parameters are accessed by pressing SET after the name of the parameter is displayed ...

Страница 54: ...o Cut out set for automatic reset 9 12 Serial Interface Parameters The serial RS 232 interface parameters menu is indicated by SErIAL Serial RS 232 interface parameters menu The Serial interface parameters menu contains parameters which determine the operation of the serial interface These controls only apply to baths fitted with the serial interface The parameters in the menu are BAUD rate sample...

Страница 55: ...ling is disabled with a sample period of 0 The sample period is indicated by SAmPLE Serial sample period parameter Press SET to choose to set the sample period The current sample period value will be displayed SA 1 Current sample period seconds Adjust the value with UP or DOWN and then use SET to set the sample rate to the displayed value SA 60 New sample period 9 12 3 Duplex Mode The next paramet...

Страница 56: ... Baths may optionally be fitted with an IEEE 488 GPIB interface In this case the user may set the interface address within the IEEE 488 parameter menu This menu does not appear on baths not fitted with the interface The menu is indicated by IEEE IEEE 488 parameters menu Press SET to enter the menu 9 13 1 IEEE 488 Address The IEEE 488 interface must be configured to use the same address as the exte...

Страница 57: ...AUTION DO NOT change the values of the bath calibration constants from the factory set values The correct setting of these parameters is important to the safety and proper operation of the bath The calibration parameters menu is indicated by CAL Calibration parameters menu Press SET five times to enter the menu 9 14 1 CTO Parameter CTO sets the calibration of the over temperature cut out This is n...

Страница 58: ...7008 Users Guide 9 16 ...

Страница 59: ...ny of the other controller functions all using remote communications equipment In addition the heater power setting and cooling capacity may be controlled using the interface To enable the heater to be switched to high using the interface the HEATER switch must be set to the LOW position The cooling power switch must be set to OFF to enable remote control 10 1 Serial Communications The bath may be...

Страница 60: ... repeatedly until the display reads ProbE This is the menu selection Press UP repeatedly until the serial interface menu is indicated with SErIAL Finally press SET to enter the serial parameter menu In the serial interface parameters menu are the baud rate the sample rate the duplex mode and the linefeed parameter 10 1 2 1 Baud Rate The baud rate is the first parameter in the menu The display will...

Страница 61: ...ed using UP or DOWN and pressing SET 10 1 2 4 Linefeed The final parameter in the serial interface menu is the linefeed mode This parameter enables On or disables OFF transmission of a linefeed character LF ASCII 10 after transmission of any carriage return The default setting is with linefeed on The mode may be changed using UP or DOWN and pressing SET 10 1 3 Serial Operation Once the cable has b...

Страница 62: ...7008 Users Guide 10 4 Table 5 Interface Command Summary ...

Страница 63: ...Digital Communication Interface 10 2 IEEE 488 Communication optional 10 10 5 Digital Communications Summary continued ...

Страница 64: ... IEEE 488 interface to read or set the temperature or access other controller functions All commands are ASCII character strings and are terminated with a carriage return CR ASCII 13 Interface commands are listed below 10 3 Interface Commands The various commands for accessing the bath controller functions via the digital interfaces are listed in this section see Table 5 These commands are used wi...

Страница 65: ...h the digital interface the front panel heater switch must be set to LOW 500 W The heater function is controlled with the F1 command Setting the parameter to 0 sets the heater to LOW 500 W and setting it to 1 sets the heater to HIGH 1000 W Sending F1 with no value will cause the controller to return a value showing what the heater setting is When the heater setting is changed a pop will be heard a...

Страница 66: ... and cooling Table 7 shows the recommended control settings for each operating temperature range The ranges may need to be adjusted depending on the bath and its particular use Table 6 Serial Power Control Functions Function Command 0 1 Heater F1 low high Refrigeration F2 off on Expansion valve F3 open closed Back pressure F4 open closed Table 7 Temperature Range Control Functions Range Heater Ref...

Страница 67: ...ill also be greater over the range If for instance 20 C and 80 C are chosen as the calibration temperatures then the bath may achieve an accuracy of say 0 2 C over the range 20 to 80 C Choosing 30 C and 70 C may allow the bath to have a better accuracy of maybe 0 05 C over the range 30 to 70 C but outside that range the accuracy may be only 0 5 C 11 2 Measuring the Set point Error The first step i...

Страница 68: ... D0 and DG were previously set for 25 229 and errH were as given above then the new values D0 and DG would be computed as 25 831 and 0028720 respectively Program the new values DO and DG into the controller The new constants will be used the next time the bath temperature is set Check the calibration by setting the temperature to tL and tH and measuring the errors again If desired the calibration ...

Страница 69: ...28530 tL 75 00 C measured t 74 901 C Compute errors errL 24 869 25 00 C 0 131 C errH 74 901 75 00 C 0 099 C Compute C0 392 25 229 25 0 25 0 75 229 25 0 25 099 0 229 25 0 75 131 0 0 D Compute CG 0028548 0 0028530 0 1 0 25 0 75 131 0 099 0 G D Figure 10 Sample calibration computations ...

Страница 70: ...7008 Users Guide 11 4 ...

Страница 71: ... to changes in bath fluid After the first year the user can set up a maintenance schedule based on the data specific to the application Heat transfer medium lifetime is dependent upon the type of medium and the environment The fluid should be checked at least every month for the first year and regularly thereafter This fluid check provides a baseline for knowledge of bath operation with clean usab...

Страница 72: ...ervice Center to be sure that the proposed method will not damage the equipment If the instrument is used in a manner not in accordance with the equipment design the operation of the bath may be impaired or safety hazards may arise The over temperature cut out should be checked every 6 months to see that it is working properly In order to check the user selected cut out follow the controller direc...

Страница 73: ...ber serial number voltage and problem description available Problem Causes and Solutions The heater indicator LED stays red but the temperature does not increase The display does not show Cut out nor displays an incorrect bath temperature and the controller otherwise appears to operate normally The problem may be insufficient heating no heating at all or too much cooling The heater power setting b...

Страница 74: ...on 1 3 for assistance The display flashes cutout and an incorrect process temperature The problem may be that the controller s voltmeter circuit is not functioning properly A problem could exist with the memory back up battery If the battery voltage is insufficient to maintain the memory data may become scrambled causing problems A nearby large static discharge may also affect data in memory Verif...

Страница 75: ...s the cause may be a defective electronic component contact an Authorized Service Center see Section 1 3 for assistance The controller controls or attempts to control at an inaccurate temperature The controller operates normally except when controlling at a specified set point At this set point the temperature displayed does not agree with the temperature measured by the user s reference thermomet...

Страница 76: ...ls The bath is not stable and the duty cycle is not constant The proportional band being too narrow typically causes this oscillation Increase the width of the proportional band until the temperature stabilizes as discussed in Section 9 7 Proportional Band The controller erratically heats then cools control is unstable If both the bath temperature and output power do not vary periodically but in a...

Страница 77: ...roller parameters or parameters are reset each time the power to the unit is removed Note Before performing the memory check you need to record the controller calibration parameters found in the CAL menu of the instrument and any user adjusted parameters that you have changed Such as the programmable set points and proportional band Memory Check Doing a memory check is the easiest way to verify th...

Страница 78: ...rmity for your instrument lists the specific standards to which the unit was tested 13 2 2 Low Voltage Directive Safety In order to comply with the European Low Voltage Directive 73 23 EEC Hart Scientific equipment has been designed to meet the IEC 1010 1 EN 61010 1 and the IEC 1010 2 010 EN 61010 2 010 standards Via Acquanera 29 22100 Como tel 031 526 566 r a fax 031 507 984 info calpower it www ...

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