Kenco Engineering Thermal Differential Switch - Manual (Page 8)

Page 8
MAINTENANCE & TROUBLESHOOTING
The sensor can be cleaned by soaking, spraying or ultrasonic cleaning. Verify material compatibility before using any
strong solvent or acid on the sensor. DO NOT sandblast or scour the sensor with abrasives. The sensor could be
damaged by this process.
TEST #1 - Power & Continuity Check
1. Remove power.
2. Remove Instrument Enclosure cover.
3. Loosen (2) Captive Screws (see Page #4)
4. Remove Electronic Module by grasping the Transformer, and pulling straight out.
5. Apply power. Verify the correct voltage at pins 7 (+ for DC) & 8 (- for DC) of Terminal Block TBB.
6. If the voltage is correct, remove power and check the fuse (F1 – see Page #5). If the fuse is bad, replace it with the
appropriate fuse.
7. If the fuse is OK, proceed to the Functionality Check.
TEST #2 - Functionality Check (Perform TEST #1 first)
1. Remove power.
2. Allow a 5 minute cool-down period.
3. Measure the resistance of each RTD (Terminal Block TBA).
a. Measure the resistance between Pins 1 & 6 – (First RTD).
b. Measure the resistance between Pins 3 & 5 – (Second RTD).
4. The resistance values for Step #3 should be 110Ω ± 10Ω @ 70ºF. Also, they must be within 5% of each other.
5. Measure the resistance between Pin #1 of Terminal Block TBA and the Instrument Enclosure. It should be greater
than 20Meg Ohms.
6. If the resistance values are not as specified above, the sensor must be replaced.
7. If the resistance values are correct, the Electronics Module must be replaced.
SPECIFICATIONS
Description Specification
AC 110Vac or 220Vac @ 50/60 Hz
Power Supply
DC 24Vdc
Output 5A DPDT – Failsafe is field selectable
Temperature Range
(Electronics)
-40ºF to 140ºF (-40ºC to 60ºC)
Standard -100ºF to 390ºF (-70ºC to 200ºC)
Medium Temp. -100ºF to 572ºF (-40ºC to 300ºC)
Temperature Range
(Sensor)
High Temp. -100ºF to 850ºF (-40ºC to 458ºC)
Pressure Range Atmospheric to 3000psig
Aqueous Liquids 0.01 – 2.5 feet/second
Hydrocarbon Liquids 0.01 – 5.0 feet/second Operating Range (Flow)
Gasses 0.1 – 500 feet/second
Response Time 0.5 to 5.0 seconds (media dependent)
Stability <0.5% from calibrated setpoint over a range of ±50ºF
Repeatability ±1.0%