TP-6322 9/0426 Section 4 Troubleshooting
4.10 Normal Source Sensing
Follow this section when the system fails to recognize
the normal power source as available by lighting the NA
LED, or when it fails to recognize normal power source
failure.
This section requires a voltmeter with a minimum
accuracy of ±1% on the scale being measured.
Initial Normal Source Sensing Troubleshooting
Use this section to initially troubleshoot normal source
sensing. This procedure requires normal source
availability.
1. Disconnect all power sources.
2. On single-phase switches, check for continuity
between terminals GND and 3PH on TB2 on the
controller assembly. If the circuit is open, install a
permanent jumper between these terminals, then
reapply power and test the system.
3. On three-phase switches, disconnect the three-
phase module from terminals GND and 3PH on
TB2 on the controller assembly and install a
temporary jumper between these terminals on the
controller assembly. Remove the temporary
jumper and reconnect the three-phase module
when normal source sensing troubleshooting and
testing is complete.
4. Disconnect the normal source. If the NA LED
remains lit for more than a few seconds, replace the
controller assembly.
5. Reconnect the normal source and check for
nominal line voltage on phase NA-NC on terminals
P1-12 and P1-15 on the controller assembly.
a. If voltage is not present on phase NA-NC on P1
on the controller, check for voltage on lugs NA
and NC on the contactor assembly. If voltage is
not present on the lugs, check the normal
source and the normal source wiring and circuit
breaker. If voltage is present on the lugs, check
the contactor wiring harness connections from
the lugs to the controller assembly.
b. If the voltage on phase NA-NC on P1 on the
controller exceeds the single-phase pickup
voltage specification in Figure 4-10 then the NA
LED on the controller assembly should light;
replace the controller assembly if the LED does
not light.
Dropout Voltage (VAC) Pickup Voltage (VAC)
160 190
Figure 4-10 Single-Phase Normal Source
Undervoltage Specifications
Use the following procedures to test normal source
sensing operation and calibration.
Normal Source Single-Phase Sensing Test
Follow the next steps to check single-phase sensing of
the normal source on both single- and three-phase
switches.
1. Disconnect the normal and emergency power
sources and the load from the transfer switch.
2. Connect a variable voltage source that ranges from
about 5% below the dropout specification to about
5% above the pickup specification to lugs NA-NC
on the contactor assembly. Increase the voltage
until the NA LED lights or the voltage is 5% above
the pickup voltage specification in Figure 4-10
3. If the NA LED does not light, replace the controller
assembly.
4. If the NA LED lights, reduce the voltage until the NA
LED turns off or is 5% below the dropout voltage
specification. If the NA LED remains lit, replace the
controller assembly. If the LED turns off, check the
voltage. If the voltage is not within ±5% of the
dropout voltage specification, replace the
controller assembly.
5. Increase the voltage until the NA LED lights. If the
voltage is not within ±5% of the pickup
specification, replace the controller assembly.
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