Type B Vital Relays - Alstom

Theory of Operation
2.4. DC LINE RELAYS
2.4.1. Neutral Line Relay
Type B neutral line relays are made in both Size 1 and Size 2. They have normal pickup
and release, are available as slow-release, slow pickup, and slow pickup and release.
In the normal pickup and release relays, the coils are full length. In slow-release and
slow pickup relays, coils of shorter lengths are used to make room for slugs on the
cores. In relays where one coil only is used (a full-length slug being on the other core),
the coil is usually placed on the lower core. Figure 2–13 shows coil connections.
2 COILS IN SERIES
B1 NEUTRAL
(FRONT VIEW)
2 COILS IN SERIES
B2 NEUTRAL
(FRONT VIEW)
12 FRONT
BACK SETS
OF CONTACTS
UPPER COIL
LOWER COIL
I
O
I
O
3A
3B
3C
3D
3E
(–)
1C
(–) I
1D
PLUGBOARD
O
JUMPER
TO SERIES COILS
(+)
I
O
6E
6C
6D
(+)
THICK WIRING IS PLUGBOARD WIRING
THIN WIRING IS RELAY WIRING.
I = "IN" LEAD
O = "OUT" LEAD
Figure 2–13. B1 and B2 Neutral Line Relays Wiring
Various resistances are available, but the nominal 500-ohm relay is recommended for
most purposes.
P1457, Rev. Nov/07 2–15 Alstom Signaling Inc.