<< Back to Home
Contact SMC
| |
| SMC TRANSFER TRIP
SYSTEM
|
(Click on image for enlarged view) |
The SMC Transfer Trip System is used to trip a remote feeder breaker when
the local substation feeder breaker detect a fault condition on the third rail or overhead
trolley line. The system can also be used as an interlock. The SMC Transfer Trip System
consists of two parts: a transmitting unit and a receiving unit. A typical installation
may have the transmitter and receiver located up to 4 miles apart. The maximum distance is
determined by the resistance of the wires used to connect the transmitter to the receiver.
The transmitter, located in the local substation, nominally produces a 100
mA constant current that is sent to the receiving unit in the remote substation to
energize the 74 relay. Interruption of the normal 100 mA current to the receiver causes
the 74 relay to drop out, providing a signal to an annunciator indicating a lack of
transfer trip capability. When the fault trip contact to the transmitter unit is closed, a
300 mA current is sent to the receiver unit which will energize the 85 trip relay in the
receiver at the remote substation. After a short time delay, the transmitter will return
to normal current. The relay can be configured to transmit a continuous trip signal.
|
 | Solid-State Design |
| 125 VDC Operation |
|
| Transmitter/Receiver Input: Fuse Protected, Surge and Transient Limited |
| High efficiency DC Chopper Constant Current Regulator |
|
TRANSMITTER:
The transmitter used in the SMC Transfer Trip System consists of input
power protection circuitry, a high efficiency DC chopper constant current regulator,
output protection circuitry, indicators for normal current output, transfer current
output, and high line resistance. The transmitter is protected with a 0.5 amp fuse. Input
power protection circuitry limits transients on the 125 VDC control power into the DC
chopper circuit and the voltage is clamped at 240 VDC.
RECEIVER:
The receiver used in the SMC Transfer Trip System consists of one relay
used for the type 74 function with two Form C sets of contacts and one relay used for the
type 85 function with two Form C sets of contacts. The input is fuse protected at 0.5 amps
and has a voltage suppressor to protect the semiconductors. Each relay has its own voltage
snubber. The input from the transmitter is fed into a full wave bridge rectifier allowing
the two wires from the transmitter to be hooked either way and still have proper
operation.
|
TRANSMITTER:
| Input Power: 125VDC -10,+50 |
| Output - Normal: 100 mA |
| Output - Trip: 300 mA |
| Efficiency: 90 % |
| Line Resistance: 0 to 300 Ohms (between
transmitter and receiver) |
| Indicators: Green LED - normal output |
| Yellow LED - transfer out |
| Red LED - high load resistance |
|
RECEIVER:
| Input:100 mA - NORMAL State, 300 mA - TRIP
State |
| Output: 74 Relay - 2 FORM C Contact sets,
85 Relay - 2 FORM C Contact sets, Contact Rating - 2 Amp at 125VDC |
|
OPERATING TEMPERATURE RANGE 0 TO 50° C
|
| Connection Diagram
|
Relay Case Dimensions
|
Click to Enlarge
|
Click to Enlarge
|
 |
For SMC Components Operation
|
A Certified Facility
|
|
