OPM_STS_400_25A_100_1GB_V011
15
GE DE STS: installation and operating manual 1.1 (GB)
Digital Energy
™
Static Transfer Switch
g
2.3 Application
The STS-400-XX is designed to operate with two electrically separated electrical power sources connected to
terminals X01 PRIMARY SOURCE and X02 SECONDARY SOURCE. The sources are connected to the STS
with a five-wire cable each (three wires for the phases, one for neutral and one for PE). Electrical parameters of
the input sources (PRIMARY SOURCE and SECONDARY SOURCE) and output external circuit (STS
OUTPUT) should meet the specifications for the STS. Three cables coming into the STS, two from the sources
and one from the load, create three outgoing lines on the diagram showed in figure 1. Lines going from the
sources are called input lines and consequently the line going to the load is called output line. Input line voltage
and output line current values should not exceed acceptable ranges.
2.4
Fuses and TVSS circuits
Fuses and TVSS units (TVSS – Transient Voltage Surge Suppressor) are placed behind the plate with MAIN
AND AUXILARY FUSES label (figure 4). Exchange of fuses and TVSS units is possible after removing that
plate (figure 6).
Fuses are placed in the primary input line and in the output line (figure 1). Each fuse is equipped with a
signalling circuit which indicates a burnt fuse. The signalling circuit is based on an auxiliary overcurrent circuit
breaker which is connected in parallel to the main fuse. When the main fuse is burnt the auxiliary circuit breaker
is energized too. In this way the state of the auxiliary circuit breaker indicates which fuse was burnt. In case of
exchanging the burnt fuse, the auxiliary circuit breaker should be set into position “on”.
Each line (two input lines and output line) is protected by TVSS units against voltage transients. In case of short
circuit inside the TVSS unit caused by a voltage transient, each TVSS is equipped with an overcurrent circuit
breaker that cuts off the circuit with a burnt TVSS. TVSS burning is indicated by a LED diode placed on the
control panel (figure 7). In case of a TVSS alarm, each TVSS unit should be checked. Each burnt TVSS unit
should be replaced as well as its fuse.
