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Preventive Maintenance<br />
4.5.7. Microchron II Timer Relay Test<br />
Follow the procedure in Table 4–13 to perform the electrical test on either the AC<br />
Microchron II Timer Relay or the Microchron II Timer (DC) Relay.<br />
Table 4–13. Microchron II Timer Relay Test Procedure<br />
Step<br />
Procedure<br />
1 Perform the visual inspection procedure in Table 4–4.<br />
2 Remove the timer electronics by following the procedure provided in<br />
Table 6–12.<br />
3 To power the relay, apply a variable current source to the coil leads (one coming<br />
from each relay coil), utilizing a meter tip plug to interface the current source<br />
with the female cap connectors on the coil leads.<br />
4 Apply saturation current as listed on the ED sheet for the relay.<br />
5 Slowly decrease current to relay to find the DROPAWAY value. This is visually<br />
determined by seeing the back contacts just make. Record this current value.<br />
6 Remove relay power.<br />
7 Reapply relay power and increase the output from the current source until the<br />
relay just makes its front contacts. Read the PICKUP value. Record this current<br />
value, this is the WORKING current.<br />
NOTE<br />
At this current value, the stop screw (residual screw) in the<br />
armature should continue to move until it hits the core surface.<br />
8 Compare measured values of the two currents with the ED sheet readjustment<br />
value. If these values are within the limits of the ED sheet, the relay is properly<br />
adjusted. If not, recheck adjustments against the foregoing instructions and<br />
retest the relay as per Steps 3 through 7.<br />
9 After the relay is checked and/or readjusted, reassemble the timer electronics<br />
by following the procedure provided in Table 6–13.<br />
P1457, Rev. Nov/07 4–17 <strong>Alstom</strong> Signaling Inc.
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