Type B Vital Relays - Alstom

Tools and Kits
The vane relay picks when there is a current phase difference between the LOCAL
winding and the TRACK winding. To pick the vane relay with the vane relay test unit the
phase angle is induced. To create the current phase difference and cause the vane
relay to pick, the test unit's LOCAL winding, powered off the supply line, has an inherent
phase shift in that the current lags the voltage by 70 or 80 degrees depending on the
relay type. Refer to the Alstom Engineering Data (ED) sheets for the vane relay to
determine the relay's Inherent Phase Angle value, see listing in Appendix A. The test
unit's TRACK winding voltage is reduced from the supply line by a very large series
resistance relative to the impedance of the track winding, so it demonstrates almost no
current/voltage phase shift. Since the current in the LOCAL winding lags the current in
the TRACK winding, this provides the phase difference to pick the relay.
Using this test unit allows the user to measure current/voltage values that closely match
the operating values of the vane relay under service conditions.
In testing some vane relays, a transformer may have to be inserted in the circuit. For
example testing relays with 5 volt TRACK windings requires adding a Universal
Transformer, P/N 31094-000-01 (Cat. A95-50) to step up the Track voltage. Refer to the
vane relay's ED sheet for details. A list of ED sheets is provided in Appendix A.
P1457, Rev. Nov/07 C–8 Alstom Signaling Inc.