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Alpha Moisture Systems dewTEC DS2000, Instruction Manual, Page: 18 / 29

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Alpha Moisture Systems dewTEC DS2000 Instruction Manual Download Page 18

 

3.5 Hysterisis 

Operation 

 
Operation of the hysterisis depends on whether the alarm is set to trip on high or low. The 
diagram below shows how the hysterisis functions in each mode. 
 

Alarm value

Alarm active

Alarm inactive

PROCESS

HIGH

ALARM

Alarm Hysterisis

Alarm inactive

Alarm value

Alarm active

Alarm inactive

PROCESS

LOW

ALARM

Alarm Hysterisis

Alarm inactive

Dewpoint

 
 
 

3.6  Resetting a latched Alarm 

 
If Alarm 1 is configured to be a latching alarm relay when it is active, it can be reset as 
follows: 
 
1 

Ensure Dewpoint is displayed 

 
 

 

 
 
 
 
 
 
2 

Press reset key (

R

) 

 
 
Note, the latched alarm cannot be reset whilst the alarm condition persists. 
 
 

dewTEC

 DS2000 User’s Manual 

 

Page 12  

Summary of Contents for dewTEC DS2000

Page 1: ...EC DS2000 dewpoint meter alpha moisture systems alpha house 96 city road bradford BD8 8ES england Tel 44 1274 733100 Fax 44 1274 733200 Email info amsystems co uk Web www amsystems co uk instruction manual ...

Page 2: ...dewTEC DS2000 User s Manual Page ii ...

Page 3: ...Dew Point Meter Installation Electrical Connections External AUTOCAL Control Section 3 Operating Instructions Start Up Front Panel Display and Keys Viewing Pre Set Parameters Alarm Settings Resetting a Latched Alarm Section 4 dewTEC DS2000 Settings AUTOCAL Factory Set Parameters Calibration Data Analogue Output Span Offset Filter Serial Communications Display Colour Lock Help Alarm Mode and Direct...

Page 4: ...dewTEC DS2000 User s Manual Page iv ...

Page 5: ...Output 7 2 7 5 Alarm Transistor Open Collector Outputs 7 2 7 6 Serial Communications Output 8 2 7 7 External Autocal Control 8 3 0 Operating Instructions 9 3 1 Start Up 9 3 2 Front Panel Display and Keys 9 3 3 Viewing Operating Mode Parameters 10 3 4 Setting the Alarms and hysterisis 11 3 5 Hysterisis Operation 12 3 6 Resetting a latched Alarm 12 4 0 Hygrometer Settings 13 4 1 Sensor Calibration A...

Page 6: ...dewTEC DS2000 User s Manual Page vi ...

Page 7: ...een or Red and can be programmed to change colour when in alarm condition Programmable via push button keys on front panel or PC optional extra Alarms Two independent fully user programmable isolated relays with open collector outputs Programmable lock out to avoid unauthorised tamper Displays maximum and minimum values Displays elapsed time from alarm condition Factory set calibration data in C F...

Page 8: ...for any obvious external damage Any evidence of damage or mishandling should be notified to your carrier immediately The items should include dewTEC DS2000 dewpoint meter Moisture Sensor packed in a metal canister instruction manual sensor connecting cable and any optional extras if ordered The sensor is packed separately in a waterproof metal canister with desiccant to protect it from excessive m...

Page 9: ... affect the sensor in a way that will impair the system accuracy It is strongly recommended that the sample should not contain particulate matter oil or other heavy hydrocarbon condensate If these components contaminate the sample system and or the measuring sensor the system response time will be lengthened although the sensor calibration will not be effected The sample must not contain Ammonia C...

Page 10: ...rocess line 2 Sample Tube This should be stainless steel for dry air or gas applications but copper or carbon steel can be used where wetter gases are to be measured If any section of the sample tube must be flexible then PTFE should be used In most cases 3mm OD 1 8 is sufficient as it provides good system response time within minimum flow 6mm OD 1 4 tube can be used where pressure drops across th...

Page 11: ... is 2 to 3 SL M Sample Exhaust The exhaust can be vented to atmosphere or returned to the process line as discussed above 2 5 Installing and commissioning the sensor It is advisable to carry out an initial purge routine of the sample loop before installing the sensor in order to remove the possibility of sensor damage on start up Referring to the sample system schematic in section 3 4 open the inl...

Page 12: ...from the front Then slide the fixing strap over the hygrometer housing from the rear of the panel until the tongues engage in the ratchets and hygrometer is firmly in place 2 7 Electrical interface connections The rear terminal houses all connections to the unit The connections are shown in the diagram below and each input is described further in the following paragraphs See the full specification...

Page 13: ...pply earth to avoid stray pick up This is very rarely a problem but if in doubt check for a voltage between the sensor body and the sensor holder before installing the sensor 2 7 3 Alarm Relay Outputs The relay outputs of Alarm 1 and 2 are single pole double throw contacts rated at 2A resistive at 120Vac or 240Vac 50 60Hz The relay contacts are inherently isolated from the instrument and from each...

Page 14: ...be capable of driving a load of 120kΩ per indicator The masterport transceiver in the passive state must have pull up pull down resistors of sufficiently low impedance to ensure that it remains in the quiescent state whilst supplying up to 100µA each to the hygrometer transceivers in the high impedance state 2 7 7 External Autocal Control An external autocal potentiometer can be added to control t...

Page 15: ...ettings Secondary Display This single character identifier highlights the parameter value being displayed not lit when normally displaying the process Dewpoint Moisture value Down key In Edit Mode decrements the flashing blinking digit in the Primary Display Scroll key Puts the Dewpoint meter into Edit Mode In Edit Mode this key selects the digit to be altered in Primary Display digit selected for...

Page 16: ...l PRESS PRESS PRESS PRESS PRESS PRESS PRESS PRESS PRESS PRESS Al arm 2 H yst eri si s val ue NOTE These displays will not appear if the Help function is disabled Initial Display at Start Up Displays your process Dewpoint Maximum High Dewpoint since last reset To reset press the R key when displayed Minimum Lo Dewpoint since last reset To reset press the R key when displayed Accumulated time that A...

Page 17: ...digit flashes P R ALM 1 ALM 2 PRESS 3 P R A LM 1 A LM 2 Use the Down key to change value of flashing digit if required P R ALM 1 ALM 2 4 P R A LM 1 A LM 2 Next digit flashes PRESS 5 Repeat steps 3 and 4 for each digit required 6 When adjustment is complete confirm new value by pressing P P R ALM 1 ALM 2 PRESS All digits will stop flashing and new valve will be displayed Display is now back in oper...

Page 18: ...GH ALARM Alarm Hysterisis Alarm inactive Alarm value Alarm active Alarm inactive PROCESS LOW ALARM Alarm Hysterisis Alarm inactive Dewpoint 3 6 Resetting a latched Alarm If Alarm 1 is configured to be a latching alarm relay when it is active it can be reset as follows 1 Ensure Dewpoint is displayed 2 Press reset key R Note the latched alarm cannot be reset whilst the alarm condition persists dewTE...

Page 19: ...s performed by comparing readings given from the hygrometer with readings obtained from a primary standard traceable to The British Standard moisture generator held at the National Physical Laboratory These comparative readings are taken after the sensor has been set to automatic calibration and the results are shown in the calibration certificate supplied with each sensor To autocal the sensor fo...

Page 20: ...irection Linear Output type Totaliser Enter the mode that you require as described in this section to change a parameter NOTE Many of the parameters are factory set during manufacture test and calibration Do not change any of these settings as your hygrometer may give erroneous readings without you knowing 4 2 1 Program Mode To enter Program Mode and to exit Program Mode Press and hold P for 3 sec...

Page 21: ...transmission Scale Minimum The lower end of the linear scale for the re transmission output expressed as the value corresponding to the minimum output signal 19999 to 19999 User adjustable setting Re transmission Scale Maximum The upper end of the linear scale for the re transmission output expressed as the value corresponding to the mamimum output signal 19999 to 19999 User adjustable setting Off...

Page 22: ...he alarms The following table gives the parameters and their sequence Adjustment Range Primary Display Identifier Flashing Description Display Description STATUS Input Range Sensor Factory setting Do not change Power Supply Frequency 50Hz 60Hz Automatically set Process High Process Low Alarm 1 Type Defines the action of Alarm 1 No Alarm User adjustable setting Process High Process Low Alarm 2 Type...

Page 23: ...Selects the output range NOTE The hygrometer is factory set to give either voltage or current outputs See the specification sheet and your order for your hygrometer setting 4 20mA User adjustable setting None Disabled Comms Enabled Not available Communications Enable Disable Only disable this function if comms is giving you a problem Not available User adjustable setting Seconds Minutes Totaliser ...

Page 24: ...trument will contain either a positive acknowledgement or a negative acknowledgement A positive acknowledgement has the character A immediately preceding the End of Message character a negative acknowledgement has the character N immediately preceding the End of Message character There are two message formats they permit instrument identification Parameter Read operations and Parameter Write opera...

Page 25: ...ame address as in the received message p is a single character parameter identifier see table below Identifier Hex Parameter Range 3A Dewpoint Depending on factory set range 3B Total Value 19999 to 99999 3C Maximum Dewpoint 19999 to 99999 3D Minimum Dewpoint 19999 to 99999 3E Elapsed Alarm 1 Time 0 to 60000 E 45 Alarm 1 Dewpoint Range Maximum to Range Minimum F 46 Alarm 2 Dewpoint Range Maximum to...

Page 26: ...be destroyed If this fails to clear the fault the sensor must be replaced Disconnect sensor cable from the instrument If reading does not change return instrument for service Re adjust autocal as described in this manual Display reads Wet Gas or free water in system Autocal wrongly set Stop gas supply and switch instrument off Check drain and inspection ports in the main system and sample system R...

Page 27: ...bed in this manual If this does not cure problem replace sensor return original for calibration Re adjust autocal as described in this manual If this does not cure problem re calibration of the system is recommended Constant Reading Condensation in Sample System Condensation will occur if the temperature of the sample system or main pipe at any point is below colder than the DP temperature of the ...

Page 28: ...lable 0 5V 1 5V 1 10V 2 10V 0 20mA and 4 20mA Accuracy 0 5 max of display value Load Impedance 500Ω max for mA ranges 500Ω min for voltage ranges 8 Serial Communications Type Serial asynchronous UART to UART Data Format Open ASCII one start bit even parity seven data bits and one stop bit Physical Layer RS485 Maximum Number of zones 99 Baud Rate Selectable 1200 2400 4800 or 9600 9 Performance Refe...

Page 29: ...Appendix B General Arrangement dewTEC DS2000 User s Manual Page 23 ...

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