Emerson 7ATB manual BYPASSING & ISOLATING continued, Turn crank

BYPASSING & ISOLATING (continued)

RETURN TO SERVICE

This procedure explains how to return the automatic transfer switch (ATS) to service after inspection and maintenance. Observe the Bypass Switch Position indicator and lights). Refer to Figures 3–7a, 3–7b, 3–8, 3–9, and 3–10.

1.Slide the transfer switch (ATS) into the enclosure (isolation contacts facing inward) until its crank pins engage the latch plates on both sides. On 4000 A substantial force is required to overcome detents on the rails. Next push in side rail carriage. On 4000 A first retract the two legs and lock them in place. See Figure 3–7b. Then close enclosure door.

Solenoid interlock prevents you from closing the isolation contacts until the ATS is in the same position as the Bypass Switch.

3.Observe which Bypass Switch Position indicator is black (NORMAL or EMERGENCY) at the Bypass Switch Handle. This indicates the source connected to the load.

4.Observe which Transfer Switch Connected To light is on (Normal or Emergency) on the door. This is the position of the Transfer Switch. If it is not in the same position as the Bypass Handle change the position of the Transfer Switch as follows:

Close the enclosure door to prevent personal injury in case of electrical system fault.

Align position indicator. Do not leave the handle in an intermediate position.

To change the position of transfer switch

Operate to NORMAL	OperatetoEMERGENCY
Turn Transfer Control	Turn Transfer Control
switch to Retransfer	switch to Transfer Test
Delay Bypass.	(hold 15 seconds).*
Connected To Normal	Connected To Emergency
light should come on.	light should comes on.

CONN

position window

* If Feature 2B time delay is used, there will be a delay

before transfer to Emergency.

TEST

ISOLATE

unfold crank

clockwise – draws in the Transfer Switch

Figure 3–8. Isolation Handle.

2. Turn the Isolation Handle clockwise (approx. 7

turns, approx. 8 turns for 4000 A) until the window

shows TEST. The ATS can be tested now without

NOTE: With Normal available, the

automatic transfer switch will not stay in the

emergency position unless Feature 3A time

delay is used (at least 30 seconds).

Do not close the isolation contacts unless the Transfer Switch (ATS) and Bypass Switch are in the same position!

5.When the transfer switch is in the same position as the Bypass Switch handle, continue turning the Isolation Handle clockwise (approx. 16 turns, approx. 12 turns for 4000 A) until the window shows CONN (connected).

load interruption (see page 2–1).

Bypass Switch E

Turn crank
clockwise	L
until
window
shows
TEST.
	N

Turn crank clockwise until window shows

CONN (connected).

Bypass Switch	E
	L
	N
ATS

ATS

Figure 3–9. ISOLATE to TEST position.

Figure 3–10. TEST to CONNECTED position.

Now continue to the next page for instructions on how to return the Bypass Handle to the OPEN postition.

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