Richards 137NP, Инструкция по эксплуатации, Страница: 30 / 53

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E. Current Transformers
One current transformer, for use with the network relay, surrounds and is mounted on each
pole of the breaker unit. Each current transformer has two windings; the phasing winding
which is energized when the breaker contacts are open by the voltage across the breaker
contacts and a secondary winding which is connected to the network relay current coils.
Current transformers are mounted directly on the main bus copper and may be removed by
moving the protector unit forward, disconnecting the wiring at the current transformer coil
terminals and removing the screws fastening the mounting brackets to the buses. When
replacing current transformers, care should be exercised to insure that they are placed on the
bus with the polarity mark H1 facing the network distribution transformer terminals. Also be
sure that all connections are in exact accordance with original connections as designated on
the wiring diagram for the particular protector involved.
F. Auxiliary Switch
Immediately below and to the right of the main breaker crosshead is mounted a unit assembly
of auxiliary switches, which are operated by a rack and gear connected to the crosshead.
These switches open and close the necessary control circuits as a function of breaker contact
position.
After approximately every 5000 operations of the protector, the auxiliary switch contacts
should be examined, and, if found to be pitted, they should be dressed with a fine file. It is
not necessary to remove contacts to dress them, however, if necessary the movable contacts
of this switch can easily be removed. Remove the stud above the wire connection. With the
contact open, push it towards the stationary contact and lift up. The contact will lift out and
can be repaired or replaced. This operation can be done with the auxiliary switch in position
on the breaker unit.
The complete auxiliary switch assembly may be removed by disconnecting the driving link,
and the control leads, and removing the two screws holding the mounting bracket to the
breaker frame. The disassembly of the auxiliary switches is not recommended due to the
many operating cams arranged in positions easily disturbed when dismantled.
After an auxiliary switch has been installed on the breaker unit, connect the rack and gear to
crosshead, (see Figure 11). Manually operate breaker to insure proper operation before
wiring. Removing screw “A” and slide will permit guide to drop down, so that rack can be
raised to provide a close adjustment on gear for the following sequence of operation.
Operate breaker manually. Contacts 1, 2, 3, and 9 should close when the arcing tips have
between 3/16 inch and 1/16 inch gap. If contacts 1, 3 and 9 should operate oppositely, then
rotate the gear approximately 180 degrees, so that these contacts will be positively closed at
the same time in the above mentioned sequence. If the proper sequence cannot be obtained,
the internal cams have been incorrectly assembled and the auxiliary switch must be removed
and the cams relocated. After the auxiliary switch contacts have been properly adjusted, the