ABB TX series Instruction Manual
TX and TS
Thermal Dispersion Level Switches
Operating instruction manual OI/TX-EN Rev. J
Flow, level, granular solids and
temperature switch
K-TEK Products
Introduction
This operating instruction manual provides the following
information:
– Calibration / set point procedure - see page 5
– Configuration - see page 7
– Installation instructions - see page 12
– Troubleshooting - see page 18
2TX Thermal Disperson Level Switches | Operating instruction manual
TABLE OF CONTENTS
1.0 PRINCIPLE OF OPERATION......................................................................................................................... 3
2.0 EXPLANATIONS ............................................................................................................................................ 4
3.0 CALIBRATION / SET POINT PROCEDURE.................................................................................................. 5
3.1 Calibrate from High TC (Thermal Conductivity) Process Conditions....................................................... 5
3.2 Calibrate from Low TC (Thermal Conductivity) Process Conditions ....................................................... 6
3.3 Trimming the TX Settings for Optimum Alarm Entry/Return to Normal Time Balance if Required .......... 6
4.0 CONFIGURATION.......................................................................................................................................... 7
4.1 Second Switchpoint Option Board (Top Board)....................................................................................... 10
5.0 INSTALLATION .............................................................................................................................................. 12
5.1 Wiring Diagram........................................................................................................................................ 12
5.2 Installation for Liquid Level Operation ..................................................................................................... 13
5.3 Installation for Flow Rates (Minimum and Maximum).............................................................................. 13
5.4 Installation for Remote Electronics.......................................................................................................... 14
5.5 Installation Setup.....................................................................................................................................15
6.0 FLOW RATE DETECTION ............................................................................................................................. 16
7.0 INTERFACE DETECTION.............................................................................................................................. 16
8.0 TEMPERATURE SWITCH OPTION............................................................................................................... 17
9.0 TROUBLESHOOTING ....................................................................................................................................18
9.1 Voltage/Resistance mesurments and Jumper Settings (Main Board) ......................................................18
9.2 Procedure for Measuring Voltage to the Sensor Using DVM (with power applied) ..................................18
9.2.1 With Power Disconnected Measure Resistance of Heater and Sensors .......................................18
10.0 APPENDIX A INSTRUMENT RANGEABILITY..............................................................................................19
10.1 TX Series................................................................................................................................................19
10.1 IX Series................................................................................................................................................ 19
11.0 APPENDIX B CONVERSION TABLE ..............................................................................................................20
12.0 APPENDIX C REMOTE MOUNTING..............................................................................................................21
13.0 APPENDIX D TX HEATING VS. DISPERSION...............................................................................................22
14.0 WARRANTY STATEMENT .............................................................................................................................23
15.0 CUSTOMER SUPPORT..................................................................................................................................24
15.1 ABB RMA Form .......................................................................................................................................25
Operating instruction manual |TX Thermal Disperson Level Switches 3
1.0 PRINCIPLE OF OPERATION
ABB’s thermal dispersion switch consists of two temperature sensors (Resistance Temperature Detectors), heater,
power supply, amplier, current generator, comparator and a relay (DPDT) for output. The type of temperature sensor
used is either a silicon semi-conductor, which is used on the standard units, or a platinum RTD which is used for high
temperature applications (see ordering options on data sheets). The two sensors are separated a short distance apart
from each other. The sensors are paired to track each other with temperature. These sensors have a resistance that is
proportional to their temperature and are known for their accuracy over a wide temperature range.
One part of the probe contains a heating element that raises the temperature of the sensor (active sensor) to a
temperature above the temperature of the medium. The other sensor (reference sensor) acts as a benchmark by
measuring the temperature of the medium. The switch can be thought of as a mass ow meter.
A constant current source is passed through both sensors to create a voltage differential that is proportional to the
amount of heat absorbed or released by the sensors. As the medium begins to rise or ow against the probes, the
molecules of the medium absorb more heat from the active sensor and the voltage differential begins to drop or as the
ow rate increases, the voltage differential will decrease (inverse relationship).
This is the basic principal behind thermal dispersion, which allows the conguration of the instrument to trip on ow,
level or temperature, to a set point or a combination of set points. The switch can be set to respond immediately to
changes in level, ow or temperature. However, as you decrease the response time, the recovery time increases.
There is an inherent time factor in any thermal dispersion switch due to the thermal conductivity of the medium, the type
of metal used and the cross sectional area of the metal surrounding the sensors. The response time can be adjusted
in a level or no-ow/ow application. But in a ow rate application, interface application or temperature application,
there is no time compensation and the unit will
not respond immediately. (See Data Sheet for
specications.)
A temperature change to the process or an
atmospheric temperature change will not affect
the setting because a change to the reference
sensor will also effect the active sensor. This
will result in an unchanged delta voltage and
therefore no change in state.
ABB’s line of thermal dispersion switches, the
TX, TQ, TS and IX are all analog switches.
This makes it a simple switch, a rugged switch,
and can be two distinct switches contained in
one housing.
4TX Thermal Disperson Level Switches | Operating instruction manual
2.0 EXPLANATIONS
The TX Thermal Dispersion switch has two RTD elements, one of which is heated by a small, low wattage electric
heating element. The thermal dispersion switch operates on the principle of a difference in thermal conductivity (TC)
between mediums (air/vapor vs. liquid or high vs. low ows of air, vapor or liquid). Once the switch has stabilized in
any given process condition, it can be adjusted such that a change (increase or decrease) in the amount of heat con-
ducted away from the heated RTD (thermal dispersion) due to a change in thermal conductivity of the process at the
sensors will cause the acative (heated) RTD to change in temperature (resistance). This change may be an increase
in temperature due to a decrease in Thermal Conductivity (TC) or a decrease in temperature due to an increase in TC.
This change is detected by the TX switch module.
This approach to calibrating the TX thermal conductivity switch may be more easily understood than the preceding
methods presented.
Understanding Switch Function:
1. An increase in ow, be it gas or liquid, or a change from gas to liquid at the sensor causes more heat to be con-
ducted away from the heated element, due to an increase in thermal conductivity at the sensor and a resultant
decrease in the “heated” element’s temperature. The TX recognizes this change as a decrease in the differ-
ential temperature between the two RTD sensors.
2. A decrease in ow or a change from liquid to a gas or vapor at the sensor results in less heat being conducted
away from the heated element (RTD) due to a decrease in thermal conductivity at the sensor and a resulting
increase in the “heated” element’s temperature. The TX recognizes this change as an increase in the differ-
ential temperature between the two RTD sensors.
3. A decision needs to be made regarding the failsafe operation required by the process control system. If fail safe
is to be incorporated, the output relay and green LED should be energized at what is determined as the normal
condition. JP3 jumpers are used to determine the relay action vs. the normal process condition. See the table on
page 6.
4. JP3 jumpers can be either in a vertical position (State A) or a horizontal position (State B) – see page 6.
Failsafe “State” required (A or B) Setting JP3 Jumpers
See page 6 to determine the JP3 relay state (A or B) jumper settings required, considering fail safe requirements of
the process. It is generally desired to have the green LED and the output relay energized with the normal process
condition at the sensor, providing an alarm should power be lost to the TX switch. Set JP3 jumpers according to the
particular application.
State A – Green LED and output relay are energized at High Thermal Conductivity (Low sensor Delta T) process
condition – high level, high ow (process conditions are above set point).
State B – Green LED and output relay are energized at Low Thermal Conductivity (High sensor Delta T) process
condition – low level, low ow (process conditions are below set point).
Relay State A – State B denitions (restated)
State A - The green LED and output relay are energized when the sensor is in the higher Thermal Conductivity (lower
differential temperature) condition. Normal process conditions for Fail Safe operation. Flow is > set point; Level is
above the sensor. The green LED and output relay are de-energized when the sensor is in the lower Thermal Conduc-
tivity (higher differential temperature) condition. Alarm process conditions for Fail Safe operation. Flow is < set point;
Level is below the sensor.
State B - The green LED and output relay are energized when the sensor is in the lower Thermal Conductivity (higher
differential temperature) condition. Normal process conditions for Fail Safe operation. Flow is < set point; Level is
below the sensor. The green LED and output relay are de-energized when the sensor is in the higher Thermal Con-
ductivity (lower differential temperature) condition. Alarm process conditions for Fail Safe operation. Flow is > set
point; Level is above the sensor.
Operating instruction manual |TX Thermal Disperson Level Switches 5
3.0 CALIBRATION / SET POINT PROCEDURE
Determining High and Low Thermal Conductivity Process conditions
I. It is usually easy to recognize the high and low thermal conductivity conditions when the switch is applied to
liquid and vapor conditions (high and low level detection). The higher TC is almost always when the sensors are
in the liquid phase.
II. There are interface applications where the high and low TC process conditions may not be so obvious.
III. The TX switch itself can be used to identify the high and low TC conditions.
A. Remove power from the TX.
B. Make connections to pins 1 and 3 of P2 (Pin 1 is nearest the green LED).
1. Temporarily insert small pieces of solid wire in P1 or P2; or,
2. Use ABB TX service plug connected to P1 on:
a. Main board (using gender changer adapter) for (single relay output); or,
b. Piggy-back board (dual set point/output, without gender changer adaptor).
c. Pin 1 is green wire; pin 3 is yellow wire on TX service plug.
C. Connect a mV meter to Pin 1 (-) and pin 3 (+)
D. Apply power to the TX. The mV read will be due to the difference in temperature between the Active
Sensor and the Reference Sensor.
E. Change the process conditions at the TX sensors from Normal to Alarm, allowing time to stabilize (5
minutes) and log these mV values.
1. Higher mV value indicates LOW Thermal Conductivity at the sensors (heat is not being
conducted away as well from the Active sensor allowing the temperature of that sensor to
increase).
2. Lower mV value indicates HIGH Thermal Conductivity at the sensors (heat is being conducted
away from the Active sensor, keeping the temperature at lower values.
3.1 Calibrate from HIGH TC (Thermal Conductivity) process conditions as follows:
JP3 State A - Green LED, output relay energized at NORMAL condition (High Thermal Conductivity (low differential
temperature) conditions at the sensors); high level (level above sensor), ow above setpoint (see table page 6)
Notes:
1. If the TX switch is operated in State A, the TX switch should be adjusted (calibrated) in the NORMAL
condition; Highest Thermal Conductivity conditions on the sensors (wet sensor, high ow); Green LED and
output relay will be energized during and after calibration.
2. CW rotation of R18 turns LED ON.
Calibration Adjustments
1. Provide the NORMAL condition (HIGH Thermal Conductivity process condition (high level (level above the
sensors), high ow)) at the sensor. Green LED and output relay will be energized after calibration.
2. Allow 5 minutes (minimum time) for switch temperature to stabilize.
3. Adjust R18 (drawing page 5) as follows:
a. If LED is On – slowly turn R18 counter clockwise (CCW) to OFF. Then turn CW until ON.
b. If LED is Off – slowly turn R18 clockwise (CW) until green LED turns ON
4. Turn R18 CW as follows for stable operation (no false alarms) (LED will be On):
a. Air – 1 full turn
b. Organics/Hydrocarbons – 2 full turns
c. Water – 3 full turns
Trimming the TX settings for optimum alarm return to normal time balance if required:
When the LED just turns ON, (3.b. above), the TX “alarm/recovery (return to normal) window” is positioned nearest
to the process’s energized LED Normal (high TC; Low mV) value. This provides the shortest possible time to recog-
nize (enter) the de-energized alarm condition, but the longest possible recovery time back to the energized (normal)
state.
Step 4 is an attempt to provide closer equal response times (time to enter alarm vs. time to recognize normal condi-
tions and exit the alarm condition) as well as stability from false alarms.
6TX Thermal Disperson Level Switches | Operating instruction manual
Note that adjusting R18 affects both alarm recognition time (time for the TX switch to recognize an alarm condition at
the sensors) as well as recovery time (time for the TX switch to recognize that the conditions have returned to normal)
by positioning the “alarm/recovery” window nearer the alarm or normal process condition mV values. Note: it is impor-
tant to allow 5+ minutes of stabilization in any new process condition to obtain repeatable time values.
1. If the alarm entry time needs to be made faster AND the alarm recovery time (time to return to normal condi-
tions) needs to be made slower, turn R18 CCW in ½-1 turn increments, moving the alarm/recovery window
nearer the Alarm (Low TC; High mV) process condition.
2. If the alarm recovery time (time to return to normal energized state) needs to be made faster AND the alarm
entry time needs to be made longer, turn R18 CW in ½ - 1 turn increments. This moves the alarm/recover
window closer to the Normal (High TC; Low mV) process condition.
3. Test the switch response after each adjustment until an acceptable balance in alarm entry time vs. recovery
time (return to normal conditions) is established empirically.
3.2 Calibrate from Low TC (Thermal Conductivity) process conditions as follows:
JP3 State B - Green LED, output relay energized at NORMAL condition (LOW Thermal Conductivity, high differential
temperature, conditions at the sensors); low level (level below sensor), ow below set point (see table page 6)
Notes:
1. If the TX switch is operated in State B, the TX switch should be adjusted (calibrated) in the ALARM condi-
tion; Highest Thermal Conductivity conditions on the sensors (wet sensor, high ow); Green LED and output
relay will be de-energized during and after calibration.
2. CCW rotation of R18 turns LED ON.
Calibration Adjustments
1. Provide the ALARM condition (High Thermal Conductivity process condition (high level (level above sensor),
high ow condition)) at the sensor. Green LED and output relay will be de-energized after calibration adjust-
ments
2. Allow 5 minutes (minimum time) for switch temperature to stabilize.
3. Adjust R18 (see drawing page 5) as follows:
A. If LED is On – slowly turn R18 clockwise (CW) until the green LED turns OFF
B. If LED is Off – slowly turn R18 counter clockwise (CCW) until the green LED turns on – then slowly CW
until it just turns OFF.
4. Turn R18 CW as follows for stable operation (no false alarms) (LED will be Off):
A. Air – ¼ turn
B. Organics/Hydrocarbons – ½ turn
C. Water – 1 full turn
3.3 Trimming the TX settings for optimum alarm entry/return to normal time balance if required:
When the R18 is adjusted such that the LED just turns off, (3.a/b. above), the TX “alarm/recovery (return to normal)
window” is positioned nearest to the process’s de-energized LED Alarm (high TC; Low mV) value. This provides the
shortest possible recovery time to recognize the energized LED Normal condition, but the longest possible time to
enter the de-energized (Alarm) state.
Step 4 is an attempt to provide somewhat equal response times (time to enter alarm vs. time to recognize normal con-
ditions and exit the alarm condition) as well as stability from false alarms. Note that adjusting R18 affects both alarm
recognition time (time for the TX switch to recognize an alarm condition at the sensors) as well as recovery time (time
for the TX switch to recognize that the conditions have returned to normal) by positioning the “alarm/recovery” window
nearer the alarm or normal process condition mV values.
Note: it is important to allow 5+ minutes of stabilization in any new process condition to obtain repeatable time val-
ues.
1. If the alarm entry time needs to be made faster AND the alarm recovery time (time to return to normal condi-
tions) needs to be made slower, turn R18 CW in ¼ - ½ turn increments. Test the switch response after each
adjustment until an acceptable balance in alarm entry time vs. recovery time (return to normal conditions ) is
established empirically.
Operating instruction manual |TX Thermal Disperson Level Switches 7
4.0 CONFIGURATION
The thermal dispersion line, TX, TQ, TS, IX and IM electronics module can be factory congured to accept power in-
puts of 90-130 VAC, 200-240 VAC at 50/60 Hz or 24 VDC. Maximum current draw with the dual switch point option is
180 ma and the maximum power draw is 5.5 Watts.
In addition, there are 6 jumper terminals JP2 through JP7 that allow you to set up the electronics for, Level, Liquid
Flow, Air Flow, Granular Solids, and Temperature.
All TX series switches can be congured to function as a window comparator. That is, to detect between two different
ow rates or two different temperatures. The switch can monitor for a combination of level and temperature, or ow and
temperature with the dual switch point option. With the dual switch point option board, the ow rate of a process can be
monitored with the millivolt output (approximately 1 volt to 3 millivolts). The millivolt output has an inverse relationship
to ow. In this conguration, the unit is two switches contained in one housing.
The output of basic unit consist of double pole–double throw (DPDT) relay. The dual switch (DS) option includes an-
other DPDT relay.
JUMPER SETTINGS FOR TX - 1000 BOARD (BOTTOM BOARD)
*DEFAULT
2. If the alarm recovery time (time to return to normal energized state) needs to be made faster AND the alarm
entry time needs to be made longer, turn R18 CCW in ¼ - ½ turn increments. Test the switch response after
each adjustment until an acceptable balance in alarm entry time vs. recovery time (return to normal conditions)
is established empirically.
8TX Thermal Disperson Level Switches | Operating instruction manual
Default Setting
Switch set for Liquid Flow (Fail Safe Low Flow)
JP 3: Relay setting as shown for State A
Energizes when above ow set-point of R18
Two Jumpers x 2mm
LEVEL OR AIR FLOW
Switch set for Level or Air Flow (Fail Safe) High Level or High
Flow
JP3: Relay set for State B
Energizes when dry or below ow set-point above setting
of R18
Two Jumpers x 2mm
Switch set for Temperature: uses only the reference sensor
(STS or RTD)
JP3: Set for State A or B (as shown)
To energize below or above setting of R18
State A: Energize when temperature is below set-point
State B: Energize when temperature is above set-point
4.0 CONFIGURATION (cont’d)
Operating instruction manual |TX Thermal Disperson Level Switches 9
LIQUID FLOW (BOTTOM BOARD)
JP3 Jumper Conguration
CONDITION State A State B
Relay Energized LED On
Fail Safe
Flow > Set-Point
Normal Condition
Flow < Set-Point
Normal Condition
Relay De-energized LED OFF Flow < Set-Point Flow > Set-Point
LEVEL OR AIR FLOW (BOTTOM BOARD)
JP3 Jumper Conguration
CONDITION State A State B
Relay Energized LED On
Fail Safe
WET or Air Flow > Set-Point
Normal Condition
DRY or Air Flow < Set-Point
Normal Condition
Relay De-energized LED OFF DRY or Air Flow < Set-Point
Normal Condition
WET or Air Flow > Set-Point
Normal Condition
TEMPERATURE (BOTTOM BOARD)
JP3 Jumper Conguration
CONDITION State A State B
Relay Energized LED On
Fail Safe
Temperature < Set-Point
Normal Condition
Temperature > Set-Point
Normal Condition
Relay De-energized LED OFF Temperature < Set-Point
Normal Condition
Temperature < Set-Point
Normal Condition
4.0 CONFIGURATION (cont’d)
2
4
1
3
1
3
2
4
1
3
2
4
1
3
2
4
2
4
1
3
2
4
1
3
10 TX Thermal Disperson Level Switches | Operating instruction manual
4.1 Second Switchpoint Option Board (Top Board)
The TX-2000 option board plugs into the TX-1000 main electronics module. It is mounted directly above the main
module. It has two 3 pole terminal blocks that connect to the board’s double-pole double-throw relay contacts. These
contacts can be set to switch at a set point that is independent of the setting on the main board.
The second set point is controlled by the board’s potentiometer R16. The board also has a 2 pole terminal block for an
amplied millivolt-volt output of the delta voltage, that is between the Active and Reference sensors. The output is ap-
proximately 3 times that of the delta voltage. The output has an inverse relationship to ow and is not linear (the output
voltage decreases as ow increases). The amplied output does not apply when used as a temperature switch.
In addition, the board also has 6 jumper terminals JP8 through JP13 that allow you to set up the electronics for Liquid
Flow, Air Flow, Level (Granular Solids & Liquid) and Temperature as follows:
Switch set for Liquid Flow - Default (Fail Safe Low)
JP11: Relay setting as shown for State A
Default: Energizes above ow set-point
Switch set for Air Flow & Level (Fail Safe High)
JP11: Relay setting as shown for State B Energizes
when DRY or below ow set–point
Switch set for Temperature: uses only the reference
sensor (STS or RTD)
JP11: Set for State A or B (as shown above)
To energize below or above setting of R16
State A: Energize when temperature is above set-point
State B: Energize when temperature is below set-point
This manual suits for next models
1
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