Pulsafeeder Pulsar DLCM - Manual (Page 108)

102
11.1.2 Tachometer Troubleshooting
The DLCM utilizes the Tachometer sensor installed in the gear box to determine motor speed. This
sensor detects the passage of 24 gear teeth per motor shaft revolution. If this device is not working
properly, the DLCM will malfunction. This typically results in the display of the {TACHOMETER /
FAILURE} or {OVER SPEED / SHUT-DOWN} message. If your DLCM displays either of these
messages, use the following procedure to trouble shoot the device:
Required Tools:
− Phillips head screw driver
− Adjustable Wrench
− Multi-meter
1. Turn off and lock out the power to the DLCM at the main panel.
2. Remove the Wiring Access cover (refer to Figure 2: Accessing the Field Wiring Board).
3. Disconnect the motor power from J3 on the Field Wiring Board (refer to Figure 4 – High Voltage
Connections).
4. Assure that the pump will not discharge fluid and will not be subject to back pressure. Take all
necessary precautions.
5. To complete this procedure, you will have to manually rotate the PULSAR drive motor. If the motor
type is TEFC (Totally Enclosed Fan Cooled), you can push against the fan blades through the shroud
to do this. If the motor type is TENV (Totally Closed Non Ventilated), you must remove the protective
cap from the end of the motor to access the motor shaft.
6. Turn on the power to the DLCM at the main panel.
7. Check the supply voltage to the Tachometer. Set your multi-meter to read DC voltage in the range of
0-10VDC. Connect the positive lead of the multi-meter to J10-1 (TACH[+]). Connect the negative
lead of the multi-meter to J5-8 (unlabeled, it is actually DC ground). You should read a value of
5.0VDC +/-0.5VDC. If you do not read this value, stop your test and contact Technical Services.
8. Check the output from the Tachometer. Set your multi-meter to read DC voltage in the range of 0-
5VDC. Connect the positive lead of your multi-meter to J10-2 (TACH[-]) and the negative lead to J5-8
(unlabeled, it is actually DC ground). Slowly rotate the pump motor observing the high and low multi-
meter readings. When the Tachometer is working properly this output will be transition from a value
below 0.35VDC when a gear tooth is near the end of the sensor to a value above 1.8VDC when it is
away from it. If these readings are obtained skip to step 17.
9. If these voltage readings are not obtained, adjust the sensor as follows.
10. Remove the conduit from the sensor housing by removing the ‘C’ clip and threading the plastic
coupling from the sensor. Note: the tachometer cord will prevent you from removing the conduit
completely. Refer to Figure 8: Tachometer and Pump Motor Thermostat Connections.
11. Remove the lock nut from the sensor housing and carefully rotate the sensor body clockwise until the
sensor bottoms against the gear, then rotate the sensor body counter clockwise 1/2 turn.
12. Slowly rotate the pump motor until the minimum multi-meter reading is obtained. If the meter does not
exhibit any voltage change either the sensor or the interface circuitry is defective. –– Do not
proceed -- Contact Technical Services ––
13. Slowly rotate the sensor body counter-clockwise a few degrees at a time until the minimum multi-
meter reading is obtained. If this reading is above 0.35 volts either the sensor or the interface circuitry
is defective. ––
Do not proceed -- Contact Technical Services ––
14. Slowly rotate the sensor body clockwise a few degrees at a time until the multi-meter reading rises
slightly (0.01 to 0.05 volts above the minimum obtained above).
15. Replace and tighten the lock nut, while maintaining the voltage reading above by holding the sensor
cable to prevent the sensor from rotating.