GE IAC77B, Руководство пользователя

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GEK-34055
INSTANTANEOUS UNIT
Select the desired range by making the proper connections at the rear of the relay (See Internal
Connections Diagram). Whenever possible, always select the higher range since it has higher continuous
rating.
2. Set the instantaneous unit to pick up at the desired current level. See �setting the Instantaneous
Unit�, ion the "Acceptance Test Section."
All the tests described above under Installation Tests must be performed at the time of installation.
In addition, if those tests described under the "Acceptance Tests Section" were not performed prior to
installation, it is recommended that they be performed at this time.
PERIODIC CHECKS AND ROUTINE MAINTENANCE
�
In view of the vital role of protective relays in the operation of a power system , tt is important
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0
that a periodic test program be followed. It is recognized that the interval between periodic checks
will vary depending upon environment, type of relay and the user's experience with periodic testing.
Until the user has accumulated enough experience to select the test interval best suited to his individual
requirements, it is suggested that the points listed below be checked at an interval of from one to two
years.
These tests are intended to e nsure that the relays have not deviated from their original setting.
If deviations are encountered, the relay must be retested and serviced as described in this manual.
TIME OVERCURRENT UNIT
1. Perform Pick-up test as described in the "Installation Section" for the tap in service.
2. Perform the Time Tests as described in the "Installation Section."
INSTANTANEOUS UNIT
Check that the Instantaneous Unit picks up at the desired current level, as outlined in the
"Acceptance Test Section."
TARGET AND SEAL-IN UNIT
1. Check that the unit picks up at the values shown in Table
XI.
2.
Check that the units drops out at 30% or more of tap value.
CONTACT CLEAN lNG
For cleaning relay contacts, a flexible burnishing tool should be used. This consists of a flexible
strip of metal with an etched-roughened surface resembling in effect a superfine file. The polishing
action is so delicate that no scratches are left, yet is will clean off any corrosion thoroughly and
rapidly. Its flexibility e nsures the cleaning of the actual points of contact. Do not use knives, files,
abrasive paper or cloth of
any kind to clean relay contacts.
SYSTEM TEST
Although this Instruction Book is primarily written to check and set the lAC relay, overall functional
tests to check the system operation are recommended at intervals based on the customer's experience.
SERVICING
TIME OVERCURRENT UNIT
If it is found during installation or periodic testing that the time overcurrent unit is out of
limits, the unit may be recalibrated as follows:
1. Rotate time dial to No.
0
time dial setting and check by means of a lamp that the contacts just close.
Where the.conta�ts
�
ust close can.be adjusted by running the stationary contact brush in or out by
means of 1ts adJust1ng screw. Th1s screw should be held securely in its support.
With the contacts just closin� at No. 0 time setting, there should be sufficient gap between the
stationary contact brush and 1ts metal backing strip to ensure approximately 1/32" wipe.
1 1
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