Under-oil arrester disconnection during test (with
arrester disconnect switch)
Eaton’s Cooper Power series arrester disconnector
provides a means of disconnecting and reconnecting an
under-oil arrester ground for transformer testing. Separate
disconnectors are used for each arrester in the transformer,
and are located on the transformer faceplate.
The arrester disconnector is operated as follows:
Operating from closed to open position (see Figure 26):
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals.
2. Unscrew handle from shaft.
3. Re-attach small diameter end of handle to shaft.
4. Push handle and shaft toward transformer until shaft
flange (adjacent to handle) is flush to sealing gland.
5. Transformer is now ready for Impulse or Applied
Potential testing.
Operating from open to closed position:
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals.
2. Pull handle and shaft away from transformer
completely.
3. Unscrew handle and re-attach with large diameter end
toward the transformer. To assure good ground contact,
the handle should be re-tightened by rotating handle
3/4 to 1 turn after handle has come in contact with seal
gland.
Under-oil arrester disconnection during test (with-
out arrester disconnect switch)
To disconnect arresters without a disconnect switch:
1. Verify that tank is grounded. De-energize transformer
from a remote upstream source. Ground all bushings
and terminals.
2. Remove tank cover following procedures in
Tank Cover
Removal and Installation
section of this manual.
3. Locate arrester ground lead pad (see Figure 27)
attached to tank wall.
4. Disconnect arrester ground leads from ground lead pad
and separate leads ends a minimum of 5” from each
other and from any part of the transformer.
5. Transformer is now ready for impulse or applied
potential testing.
To reconnect:
1. Reconnect arrester ground leads to ground lead pad.
2. Re-install tank cover as outlined in
Tank Cover
Removal and Installation
section of this manual.
CAUTION
Before opening the transformer tank for internal
maintenance, read the Insulating Liquid Maintenance
section in this manual. This section explains safety
precautions that should be taken and gives instructions
on how to prevent insulating liquid contamination.
Figure 26. Arrester disconnector operation.
Figure 27. Under-oil arrester jumper ground lead pad
with ground leads.
18
Three-phase pad-mounted compartmental type installation and maintenance instructions
MN202001EN August 2015
