Global Power Technologies
SERVICE AND MAINTENANCE
05585 rev11 | Model 8550-SD
Page 34 of 53
Figure 19 – Automatic Shut-off Components
If your Model 8550-SD TEG is experiencing intermittent shutdowns or does not start reliably, follow
these steps to troubleshoot the Automatic Shut-Off system.
1.
Check that the thermocouple sensor is installed correctly in the Burner Plate assembly.
2.
Verify that the connection between the thermocouple and the Overtemperature Shutdown Relay
Assembly is tight.
3.
Ensure that the connection between the shutdown relay and the shut-off valve is tight.
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 4.3.