ABB COV-6, Инструкция

Страница: 7 / 21

41-116.1A
7
With the time dial set on “O”, wind up the spiral
spring by means of the spring adjuster until
approximately 6-3/4 convolutions show.
The spiral spring can be adjusted with the spring
shield in place as follows. One slot of the spring
adjuster will be available for a screwdriver in one
window of the front barrier of the spring shield. by
adjusting this slot until a barrier of the spring
shield prevents further adjustment, a second slot
of the spring adjustment will appear in the win-
dow on the other side of the spring shield barrier.
Adjusting the second slot in a similar manner will
reveal a third slot in the opposite window of the
spring shield.
Adjust the control spring tension so that the mov-
ing contact will leave the backstop at tap value
c 1.0% and will return to the backstop at
tap value current - 1.0%.
C. Time Curve Calibration – Install the permanent
magnet.
Apply the indicated current per Table 1 for the
permanent magnet adjustment (e.g., COV8, 2
times tap value) and measure the operating time.
Adjust the permanent magnet keeper until the
operation time corresponds to the value of Table
1.
For type COV-11 relay only, the 1.30 times tap
value operating time from the number 6 time dial
position is 54.9
±
5% seconds. It is important that
the 1.30 times tap value current be maintained
accurately. The maintaining of this current accu-
rately is necessary because of the steepness of
the slope of the time-current characteristic (Fig-
ure 8). A 1% variation in the 1.30 times tap value
current (including measuring instrument devia-
tion) will change the nominal operating time by
approximately 4%. If the operating time at 1.3
times tap value is not within these limits, a minor
adjustment of the control spring will give the cor-
rect operating time without any undue effect on
the minimum pick-up of the relay. This check is to
be made after the 2 times tap value adjustment
has been completed.
Apply the indicated current per Table 1 for the
electromagnet plug adjustment (e.g. COV-8, 20
times tap value) and measure the operating time.
Adjust the proper plug until the operating time
corresponds to the value in Table 1. (Withdraw-
ing the left-hand plug, front view, increases the
operating time and withdrawing the right-hand
plug, front view, decreases the time.) In adjusting
the plugs, one plug should be screwed in com-
pletely and the other plug run in or out until the
proper operating time has been obtained.
Recheck the permanent magnet adjustment. If
the operating time for this calibration point has
changed, re-adjust the permanent magnet and
then recheck the electromagnet plug adjustment.
7.2. Indicating Contactor Switch (ICS)
Initially adjust unit on the pedestal so that armature
fingers do not touch the yoke in the reset position
(viewed from top of switch between cover and frame).
this can be done by loosening the mounting screw in
the molded pedestal and moving the ICS in the
downward position.
a) Contact Wipe – Adjust the stationary contact so
that both stationary contacts make with the
moving contacts simultaneously and wipe 1/64”
to 3/64” when the armature is against the core.
b) Target – Manually raise the moving contacts and
check to see that the target drops at the same
time as the contacts make or up to 1/16” ahead.
The cover may be removed and the tab holding
the target reformed slightly if necessary. How-
ever, care should be exercised so that the target
will not drop with a slight jar.
c) Pickup – The unit should pickup at 98% rating
and not pickup at 85% of rating. If necessary, the
cover leaf springs may be adjusted. To lower the
pickup current use a tweezer or similar tool and
squeeze each leaf spring approximately equal by
applying the tweezer between the leaf spring and
the front surface of the cover at the bottom of the
lower window.
If the pickup is low, the front cover must be
removed and the leaf spring bent outward
equally.
7.3. Indicating Instantaneous Trip (IIT)
Initially adjust unit on the pedestal so that armature
fingers do not touch the yoke in the reset position
(viewed from top of switch between cover and frame).
This can be done by loosening the mounting screw in
the molded pedestal and moving the IIT in the down-
ward position.