Maintenance - HPS EnduraCoil 1.2 KV Manual De Instrucciones

Field Testing (continued)
Transformer Minimum
Voltage Class Clearance
(mm)
1.2 KV 25
2.5 KV 50
5.0 KV 100
8.7 KV 130
15 KV 200
18 KV 250
25 KV 300
34.5 KV 400
Note: "Some specific components of a transformer may require
clearances different than those indicated above. For those
exceptions, refer to the instructions provided in the assembly
drawings or installation procedure."

Maintenance

DANGER
Failure to de-energize and ground the transformer
before opening the enclosure and/or working
on the transformer will result in serious personal
injury or death.
insulation resistance. Experience to date indicates that 2
megohms, (one minute reading at approximately 25°C)
per 1000 volts of nameplate voltage rating, but in no case
less than 2 megohms total, may be a satisfactory value
for insulation resistance. Insulation megger test (500 V or
1000 V DC). Tests to be done between:
Minimum
Clearance
(in.)
1
2
Note: If the transformer core is isolated, then the core
4
strap between the core and the top core clamp, must be
disconnected before taking the measurement from core to
5.3
ground.
8
7. Turns ratio test for full winding and for all tap positions
10
12
8. Polarity or phase relationship.
16
9. Resistance measurements of windings.
10. Ensure that minimum clearances are maintained for all
current carrying parts including windings, internal cable
connections, PT's, NGR, CT's, auxiliary transformer and bus
bars.
The following table may be used as a guide for minimum
clearance for altitude not exceeding 1000 m (3300 ft).
Above 1000 m (3300 ft) consult factory.
The transformer must be de-energized prior to any
maintenance. It is also recommended that all terminals
be grounded and include a lockout/tagout procedure.
Periodic Inspection and Maintenance:
Generally, very little maintenance is required for dry-type
transformers. However, periodic care and inspection is required
to ensure long-term, successful operation. The frequency
of inspection will depend on the conditions where the
transformer is installed.
For clean, dry locations, an annual inspection is normally
sufficient. For other locations where the air is contaminated
with dust or chemical vapors, inspection at three or six month
intervals may be required.
With the transformer de-energized, remove all access panels
on the enclosure and ground the terminals. Inspect for dirt
particularly on insulating surfaces or any surface which tends
to restrict air flow. Insulators, terminals and terminal boards
should be inspected for discharge (tracking), breaks, cracks or
burns and tightness of hardware. It is necessary to clean these
parts to prevent flashover due to the accumulation of the
contaminant.
Evidence of rusting, corrosion, and deterioration of the paint
should be checked and corrective measures taken where
necessary. Fan motors, and other auxiliary devices should also
be inspected and serviced.
LV to HV + Ground
HV to LV + Ground
Core to Ground (if the core is isolated)
13
IOMGCAS / May 2014