Transformer Module - Toshiba GRT100 Series Instruction Manual

3.1.2

Transformer Module

The transformer module (VCT module) insulates between the internal and external circuits
through an auxiliary transformer and transforms the magnitude of AC input signals to suit the
electronic circuits. The AC input signals are as follows:
 three-phase currents (I a , I b and I c ) for a winding
 neutral current (I N ) for a winding
 phase-to-phase voltage
Figure 3.1.4 shows a block diagram of the transformer module. There are 8 to 12 auxiliary CTs
and 1 auxiliary VT mounted in the transformer module depending on the relay model. (For the
correspondence between the relay model and number of AC input signals, see Table 3.2.1.)
The transformer module is also provided with an IRIG-B port. This port collects the serial
IRIG-B format data from the external clock for synchronization of the relay calendar clock. The
IRIG-B port is insulated from the external circuit by a photo-coupler. A BNC connector is used as
the input connector.
I a1
I b1
I c1
I N1
I a2
I b2
I c2
I N2
V
IRIG-B port
External
clock
BNC connector
Figure 3.1.4 Transformer Module (e.g. models 101, 102)
 48 
6 F 2 S 0 7 8 9
Signal
processing
module