TERASAKI AME Series, Instruction Manual

Page: 27 / 40

KRB-5200h
-21-
How to change the OCR settings:

When the ACB is equipped with the XMD4M motor operator, remove the operator before
changing the settings.
For procedures for removing and mounting the operator, see [3] Before and After Checking the
Trip Settings , XMD Series Motor Operator - Operating Instructions.
①
Remove the sealing label from the OCR transparent cover, unscrew the cover fixing screws, and
the remove the cover.
②
Turn a setting dial with a flat-head screwdriver so that the arrow points to a position you wish.
The scales indicate the I
1
and I
2
values in terms of multiples of the generator rated current In.
The setting result is the same within the same zone division (see Fig. 13).
③
Change the imprinted set value(s) to the new setting.
④
Reattach the transparent cover.
⑤
Test the OCR for tripping characteristics according to Section 5.2.
5.2 OCR Field Tests
5.2.1 Tests with Current Applied to the Main Circuit
A single-phase, large current is directly applied to the ACB main circuit to check for the long
time-delay characteristics.
Caution

OCR field tests must be performed by competent persons.

Never touch the live terminal parts.
Otherwise, electric shock may result.
Before performing the tests:

Remove the XMD4M motor operator when it is mounted on the ACB. The XMD4M motor
operator is a hinged type.
For procedures for removing and mounting the operator, see [3] Before and After Checking the
Trip Settings , XMD Series Motor Operator - Operating Instructions.

Apply voltage between auxiliary circuit terminals U
1
and U
2
when the UVT is used.
How to test the OCR:
①
Stop the generator and open a disconnector or the like to isolate all sources of power/voltage
from both the primary and auxiliary circuits.
②
Connect a large-current source to the ACB main circuit terminals.
Caution : To check the OCR characteristics for each pole, apply current to the relevant pole
only. When the generator rated current (In) is 63 A or less, apply current to the poles of R and
S phases, T and S phases, or T and R phases while connecting the two poles in serial.
Connection of three poles in serial may cause premature activation of the short time-delay trip
function if the trip pick-up current is 1n x 3 or less. Avoid such a connection scheme. Use
one-pole connection or two-pole serial connection for the testing.
A
～
ACB
Ammeter
Large-current source
●
Use an ammeter with
high accuracy.