Type B Vital Relays - Alstom

Theory of Operation
2.5.3. Lamp-Control Relay
Type B lamp-control relays, made in Size 1 only, regulate lamp circuits at highway
grade crossings protected by flashing lights. The lamp-control contacts in space 1
handle up to 15 amperes at 12 volts. The regular duty contacts in space 3 are for other
circuits.
When the relay is deenergized, the contact pusher in space 1 drops away from the
lamp-control contact fingers. With this design, oscillations of the armature due to its
striking the stop are not transmitted to the contacts when the relay is de-energized. The
armature is completely disconnected from the contact fingers.
Coil resistance is lower than the resistance of regular line relays to obtain fast pickup,
opening the back contacts as rapidly as possible. Figure 2–29 shows standard wiring
connections.
(FRONT VIEW)
36
LAMP
CONTROL
CONTACTS
15
14
13
12
35
34
33
32
REGULAR
FRONT-BACK
CONTACTS
31
I
O
I
O
3A
3B
3C
3D
(–)
3E
(+)
THICK WIRING IS PLUGBOARD WIRING.
THIN WIRING IS RELAY WIRING.
I = "IN" LEAD
O = "OUT" LEAD
Figure 2–29. Lamp-Control Relay Wiring
P1457, Rev. Nov/07 2–32 Alstom Signaling Inc.