Type B Vital Relays - Alstom

Theory of Operation
2.5.6. Code Rate Transmitter Relay
Type B code rate transmitter relays are built only in Size 2. This relay has an oscillating
armature secured to a vertical shaft that is supported at both ends by bearings. Affixed
to the upper part of the shaft is one cam. The cam opens and closes sets of contacts.
Below the cam is an armature positioned between two pole pieces. Below the armature
is a spiral spring. These parts form the rotor for the relay.
COIL
D-C VOLTAGE
APPLIED HERE
COIL CONTACT
BACK CODING
CONTACTS
CLOSED ON
POWER STROKE
LOWER CAM
POLE PIECES
UPPER CAM
SHAFT
FRONT CODING
CONTACTS
CLOSED ON
BACK STROKE
WEIGHT DISC
ARMATURE
POSTION
(POWER
STROKE)
ARMATURE POSITION
(BACK STROKE)
ARMATURE
IN DEENERGIZED
POSITION
SPIRAL COIL
SPRING
POWER STROKE
(COUNTERCLOCKWISE)
BACKSTROKE
(CLOCKWISE)
Figure 2–34. Code Rate Transmitter Relay Operation
P1457, Rev. Nov/07 2–37 Alstom Signaling Inc.