Type B Vital Relays - Alstom

Preventive Maintenance
4.5.11. Switch-Overload Relay Test
The switch-overload relay requires special adjustment. See specific ED sheet for exact
details and operating values.
Table 4–17. Switch-Overload Relay Test Procedure
Step
Procedure
1 Perform the visual inspection procedure in Table 4–2.
2 See specific ED sheet for specifications.
3 Apply the minimum specified operating current to the terminals of the pick up
winding (low resistance) with positive energy on 3C and negative energy on 3D.
After 1½ minutes back off overpressure spring until relay picks. Lock spring at
this setting.
4 Allow relay to cool at least 10 minutes.
5 Apply the minimum specified operating current to the terminals of the pick up
winding for 1½ minutes. Relay must not pick. After 1½ minutes, quickly increase
current to maximum pick up current. Relay must pick up. Remove power.
6 Check high resistance winding to insure the PICKUP and WORKING current
value is within specified limits.
P1457, Rev. Nov/07 4–21 Alstom Signaling Inc.