Global Power Technologies
SERVICE AND MAINTENANCE
302954 rev0 | Model 8550-RU
Page 35 of 53
If no installation issues are identified, verify system operation as follows:
1.
Press and hold the button on the shut-off valve to start the TEG. Keep the button held down for
the entire duration of these tests. Allow the power unit voltage to climb above 14 Volts before
proceeding.
2.
Disconnect the thermocouple fitting from the Shutdown Relay Assembly. Using a voltmeter,
measure the voltage between the cap in the center of the thermocouple fitting and the sensor
case. A healthy thermocouple will have a voltage between 15 and 30 millivolts. If the
thermocouple signal falls below this range, or if no continuity is observed, then the thermocouple
should be replaced.
NOTE: When replacing the thermocouple and using anti-seize on the burner fitting, ensure
that only high-temperature anti-seize is used.
3.
Reattach the thermocouple fitting to the Shutdown Relay Assembly. Then detach the connection
between the Shutdown Relay and the Shut-Off Valve. Perform the same voltage measurement
between the cap and the sensor case of this fitting. The millivolt reading should be about the
same as the reading from the previous step. If the voltage reading drops significantly from the
previous measurement, the Shutdown Relay may need replacement to prevent nuisance
shutdowns.
4.
If no voltage can be observed at all, then check the shutdown relay power. Refer to Section 3.3.
5.
If the shutdown module is outputting at least 12 Volts and the thermal cut-off has not opened,
then the shutdown relay is faulty and should be replaced.
6.
If no problems have been detected with the thermocouple signal but the shut-off valve still
cannot hold itself open, then the valve itself should be replaced.
NOTE:
When replacing the Shut-off Valve, ensure that you do not introduce any thread
sealing compound or other contaminants into the piping. Make sure to check for fuel
leaks.
5.9
POWER UNIT TESTING
The procedure below is designed to evaluate the conditions of the Power Unit and to determine its
operating point. This procedure should only be done if a problem with the Power Unit is suspected, it
serves no other purpose.
Open circuit voltage and internal resistance test:
The purpose of this test is to determine the momentary open circuit voltage (V
oc
) of the Power Unit
from which the internal resistance (R
INT
) can be calculated. For this test to be accurate, the TEG must
have been operating for the past 12 hours.
1.
Measure and record the Power Unit current (I) at terminals 6(+) and 7(-) of TB-1.
2.
Attach a voltmeter to read the Power Unit voltage at terminals 6(+) and 4(-) of TB-1. The
voltmeter leads must be attached to these terminals because you will need both hands free to do
the open circuit test.
3.
Measure and record the Power Unit loaded voltage (V
L
).