Alpha Technologies 255A Bypass Switch - Manual (Page 9)

7 0200018-J0 Rev C
1
3
5
2
4
6
7 8
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AUXILIAR Y S WITC H
A1
A2
A3 A4
A5 A6
A7 A8
A1
A3
A5
A7
A2
A4
A6
A8
#14AWG
R E D
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C LOS E D B E TWE E N
P OS ITIONS
NOR M
B Y P
Figure 1 — Auxiliary contacts
3.2 Auxiliary Contacts for Remote Monitoring
The operation of the Alpha MBS is "make-before-break". The auxiliary contacts are available to generate
an alarm if a "caught in transition" condition occurs.
The auxiliary switch contacts are located below TB3 in the interior of the Alpha MBS – see Figure 1.
Table A shows the condition of these contacts for all possible states of the bypass switch.
The System Schematic is shown in Chapter 6 on page 14.
Table A — Auxiliary switch truth table
MBS Function
BYPASS A1-A2 (BYP) Closed
UPS A3-A4 (UPS) Closed
CAUGHT IN
TRANSITION
A5-A6 Closed between positions
A7-A8 Closed between positions
Table B — Auxiliary Contacts – Electrical Ratings
Voltage Rating 250 Vac (max)
Current Rating 15 A