Rockwell Automation 1512A MV Controllers - 800A One-High Cabinet - Manual (Page 68)

5-20 Maintenance
1512A-UM102B-EN-P – June 2013
Adjusting the Normally Closed (ISb) Contacts
1) Move the isolation switch handle to the OFF (open) position.
2) Loosen the bolt holding the inside cam to the shaft. Do not loosen the
bolt entirely. The cam should not be able to rotate freely on the shaft.
3) Insert a 0.25 in. (6.35 mm) diameter pin into the cam groove
between the cam follower and the end of the cam groove.
4) Adjust the cam on the shaft so that the gap from the cam follower to
the end of the cam groove is the width of the pin — 0.25 in. (6.35 mm).
5) Tighten the bolt that holds the cam to the shaft. Move the isolation
switch handle to the OFF position and recheck the gap using the pin.
6) Operate the handle several times, then recheck the 0.25 in. (6.35
mm) clearance between the end of the cam groove and the follower
pin for both cams.
7) Verify that auxiliary contact ISb is closed when isolation switch
is open. Verify that ISb contact is open when isolation switch is
closed.
Adjusting the Change-of-State Point
This procedure sets the secondary electrical inter-
lock. When properly adjusted, the electrical interlock
is designed to open the control power circuit before
the isolation switch opens as the handle is moved to
the OFF position.
1) Once the auxiliaries have been adjusted, move the isolation switch
handle to the ON position.
2) Connect a conductivity measuring device across the closed auxil-
iary contacts.
3) Slowly move the isolation switch handle towards the OFF position
and observe the point at which the movable isolation switch blades
separate from the incoming line stabs. The auxiliary contacts must
change state from the closed to open position before the isola-
tion switch blades lose contact with the incoming line stabs. This
prevents the isolation switch from being opened while the unit is
energized and under load conditions.
The auxiliary contacts must be properly adjusted
to avoid opening the isolation switch under load
conditions. Improper adjustment may result in
damage to the equipment and/or severe burns, injury
or death to personnel.
4) If the auxiliaries do not change state before the isolation switch
opens, repeat the auxiliary contacts adjustment procedure (see page
5-18).
Emergency
Circumventive Procedure
for Power Cell Entry (cont.)
Isolation Switch Auxiliary Con-
tacts (cont.)
I M P O R T A N T I M P O R T A N T
A T T E N T I O N A T T E N T I O N