Installation and User Manual

1.5System Major Components

Source #1 CB1

Input isolation molded case switch with magnetic trip for isolating SCR static switch

 

#1 and associated components from source S1.

Source #2 CB2

Input isolation molded case switch with magnetic trip for isolating SCR static switch

 

#2 and associated components from source S2.

Output CB3A

Output isolation molded case switch with magnetic trip for isolating both static switch

 

sections from the load.

Output CB3B

Optional, redundant output isolation molded case switch with magnetic trip (paral-

 

leled with CB3A) for isolating both static switch sections from the load.

Source #1 Bypass CB4

Maintenance bypass molded case switch with magnetic trip for bypassing the static

 

switch section and connecting the load directly to source S1.

Source #2 Bypass CB5

Maintenance bypass molded case switch with magnetic trip for bypassing the static

 

switch section and connecting the load directly to source S2.

Keyed Interlocks

Provided on the two bypass switches to prevent closure of both at the same time.

 

An optional interlocking scheme is available for additional keyed interlocks on the

 

source isolation switches to ensure that, prior to bypassing to a particular source,

 

the STS transfers the load to that source if the load is not already being powered by

 

that source. On closure of a bypass switch, the control logic will also shunt trip

 

opposite bypass and input isolation switches if necessary to prevent cross-connec-

 

tion of the two sources.

SCR Static Switch Assy.

Three heatsink assemblies containing six pairs of “hockey-puck” SCR's. Switch #1

 

and #2 (each having 3 pairs of SCR's) automatically switch the load to either source

 

S1 or S2.

Control Electronics

The microprocessor-based core control uses FPGA’s for input and output signal

 

processing and control sequencing to optimize sensing time.

Front Display Panel

The LCD screen, pushbuttons and LED mimic diagram make up the display.

Gate Drive & Acq. PCA

Independent gate drive and acquisition circuits for each sources SCR switch.

Backfeed Protection Assy

A separate redundant circuit for each source provides backfeed protection to ensure

 

that there is no cross-connection between the two sources in the event of a shorted

 

SCR on the inactive source with the upstream circuit breaker open.

TVSS Assemblies

Optional Transient Voltage Surge Suppressor on each source input.

Triple-Redundant

 

Control Power Supplies

Three, independent DC control power supply assemblies (fed from each of the two

 

sources and the STS output) provide redundant DC control power.

CB Control Assembly

A separate circuit supplies DC control power (fed directly from the output terminals)

 

for shunt-tripping the power switches CB1-5 and for supplying EPO power even in

 

maintenance bypass mode.

Output Snubber Assembly

Provides preload under no-load conditions.

Communications Card Cage Relay card providing programmable contacts (6 outputs/2 inputs) and JBUS card for RS232 or RS485 connections. Two slots available for options.

Customer Terminal Block Terminals for connection of remote Emergency Power Off (EPO) and Source Loss Test switch.

Fans (400/600A Models only) Ventilation fans provide forced-air cooling in the 400/600A models. 200A models are convection cooled.

86-504004-00 B03

Introduction

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