Dwyer PMT - Manual (Page 21)

Particulate Monitoring Systems
Installation & Operating Manual
Document No. 210-1015-F Page 15 ©2007
Control Unit Zero Check
1. Disconnect power to the control unit.
2. For a two piece configuration, open the enclosure cover and unscrew the
coaxial cable connector from the control unit. Leave the connector inside
the control unit enclosure. Make sure the connector does not slip down into
the conduit. The one piece configuration requires only that the “Zero
Button” be pressed and held after opening the enclosure cover to generate a
zero test reading.
3. Close the enclosure cover.
4. Re-apply power to the control unit and allow the reading to stabilize for 1-2
minutes.
5. Monitor the transmitter’s mA output. Its scaled value should be well below
its specified minimum detection level. If the control unit passes this check,
there are no false signals entering the control unit. For one piece
configurations the mA output should be monitored while the zero button is
pressed and held.
Pass:
1. Disconnect power from the control unit.
2. Open the enclosure cover and re-attach the coaxial cable connector to the
control unit.
3. Close the enclosure cover and proceed to the Coaxial Cable Zero Check.
Fail:
1. If a zero reading cannot be obtained, close the enclosure cover and contact
the factory for further assistance.
Coaxial Cable Zero Check (Two Piece Configuration Only)
1. Disconnect power to the control unit.
2. Open the sensor enclosure cover and disconnect the coaxial cable center
conductor from the sensor probe end. Do not disconnect the coaxial cable
shield. Do not remove the probe from the process. Leave the coaxial cable
center conductor ring terminal hanging in free space within the sensor
enclosure (do not isolate it with tape) and close the cover.
3. Re-apply power to the control unit and allow the reading to stabilize for 1-2
minutes.
4. Monitor the transmitter’s mA output. Its scaled value should be well below
its specified minimum detection level. If the coaxial cable passes this check
then there are no false signals entering the coaxial cable.