Emerson 7000 SERIES ATB manual Bypassing & Isolating, To Bypass Normal Source

SECTION 3 BYPASSING & ISOLATING

BYPASSING

This procedure explains how to Bypass the closed Automatic Transfer Switch contacts. Bypassing is re- quired before the ATS can be tested or isolated. The Bypass Switch must be in the AUTOMATIC POS (posi- tion) and the Isolation Handle must be in the connected position (turned clockwise until it stops). The CON- NECTED light should be on.

1.Observe which Automatic Transfer Switch CLOSED ON light is on (NORMAL or EMERGENCY) on the STATUS INDICATOR panel. This light indicates the source connected to the load.

2.Bypass to the same source connected to the load as follows (select direction). See Figure 3-1, Figure 3-2, and Figure 3-3.

Figure 3-1. Bypass Handle.

To Bypass Normal Source

Push in the Bypass Handle then turn it counterclockwise to BYPASS POS. The By- pass Switch CLOSED ON NORMAL light should come on. *

Figure 3-2. Bypass to Normal.

To Bypass Emergency Source

Pull out the Bypass Handle then turn it counterclockwise to BYPASS POS. The By- pass Switch CLOSED ON EMERGENCY light should come on. *

Figure 3-3. Bypass to Emergency.

The Automatic Transfer Switch can now be put in the TEST or OPEN position. See ISOLATING.

*NOTE: When Acc. 66A is specified, the handle operation is reversed. Follow instruction on the door.

ISOLATING

This procedure explains how to isolate the Automatic Transfer Switch. Isolating is required before any service work can be performed on the ATS. Observe the ATS POSITION lights on the STATUS INDICATOR panel.

1.Bypass the closed Automatic Transfer Switch contacts. See BYPASSING.

2.Isolate the Automatic Transfer Switch as follows. Refer to Figure 3-4 and Figure 3-5.

Isolation Handle installed through enclosure door

Figure 3-4. Isolation Handle.

Bypass–Isolation Switch is energized. Do not touch isolation contact fingers; shock, burns, or death could result.

To Isolate the Automatic Transfer Switch

a.Open the enclosure door and remove the Isolation Handle stored on the right side of the carriage frame. Close the door. Insert the Isolation Handle into the shaft (through the door).

b.Turn Isolation Handle counterclockwise (about 6 or 7 turns) until the TEST light comes on.

c.Continue turning Isolation Handle counterclock- wise (approximately 10 or 11 turns) until it stops and DISCONNECTED light comes on, TEST light off.

d.Remove Isolation Handle and store it inside the enclosure on the right side of the carriage frame.

Figure 3-5. Isolated (DISCONNECTED) ATS.

The Transfer Switch can now be removed for inspection and maintenance. See page 3–2.

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