Type B Vital Relays - Alstom

Theory of Operation
The lower cam actuates contacts on either side of the cam to alternately open and close
once for each rotor oscillation. Rate of armature oscillation depends on the mass of the
armature and the length of the spiral spring. Relays with nominal rates of 50, 75, 120,
180, 220 and 270 cycles per minute are available.
CAUTION
Code rate transmitter relays are shipped with a locked rotor. This lock
must be released before the relay is placed in service. For more
information, see "INSPECTION AND INSTALLATION," Section 3.
Code rate transmitter relays have a single nominal 150-ohm resistance coil that
operates in a 10-volt circuit. A nominal 1000-ohm resistance is shunted across the coil
to absorb the inductive voltage surge, which occurs each time the contact opens the coil
circuit.
In addition, a 0.25 mfd capacitor and a 150-ohm resistor form an RC network that is
shunted across the coil contact to suppress arcing and eliminate electro-magnetic
interference. See Figure 2–35.
FRONT OF RELAY
( - )
16 26 36 46 56 66
11 21 31 41 51 61
- +
1B 1H 2B 2H
5H 5F 6H 6F
6E
( + )
THICK WIRING IS PLUGBOARD WIRING.
THIN WIRING IS RELAY WIRING.
Figure 2–35. Code Rate Transmitter Relay Wiring
P1457, Rev. Nov/07 2–38 Alstom Signaling Inc.