Type B Vital Relays - Alstom

Theory of Operation
VANE
CONTACTS
PUSHER
(FOR CONTACTS)
RELAY BASE
LOCAL COIL
WINDING
STOP
ROLLER
SHAFT
BEARING
COUNTERWEIGHT
Figure 2–43. Vane Relay Components
The local coil may be double-wound so that the two windings can be hooked up in
series or in parallel. When connected in parallel, each winding operates at half-voltage,
and it becomes possible to connect a phase-shifting device, should track operating
conditions make it necessary. Track windings are furnished the same way.
Examples of phase shifting devices are:
• track filter (P/N 58496-117-01)
• local filter (P/N 58496-118-01)
The local filter is a combined two-section series tuned and parallel tuned filter. The track
filter contains a fuse, a capacitor, and a variable inductor.
The local and track filters are used to prevent line induced noise and traction energy
from interfering with track circuit performance. The filter acts as a partial phase shifter to
help establish a 90 degree phase shift between the track and local windings of the track
relay. This is especially important at minimum ballast conditions.
P1457, Rev. Nov/07 2–45 Alstom Signaling Inc.