Custom Bushings

Current Ratings

Voltage Ratings

Polycast type tests the bushings it supplies, and will assist its customers in determining optimum conductor sizes and arrangements for their applications. However, it is not practical to pre-determine the absolute maximum current ratings for every bushing and for every possible bushing variation, or every condition of use. Thus, we specify a conservative nominal current rating
or, where experience allows
a practical current range
for each bushing, based upon:
1) Type tests
2) Test data from equivalent units
3) Industry standards

Because the conditions of use of any bushing is beyond our control, it is always the responsibility of users to ensure that the current carrying capability of any bushing they use is not exceeded in their application.

Polycast
Standard
Ratings

Transformer Bushings

Switchgear Bushings

Nom.
Voltage
Class
kV

Low
Freq
Dry
kV

Impulse
(BIL)
kV Crest
1.2x 50us

Chopped
Wave
kV Crest
( us)

Nom.
Voltage
Class
kV

Low
Freq.
Dry
kV

Impulse
(BIL)
kV Crest
1.2x50us

0.6

1.2 ²

36 (1.0)

2.5 ²

54 (1.5)

5.0 ²

69 (1.5)

4.76

8.7 ²

88 (1.6)

8.25

15.0 ²

110 (1.8)

15.0

15.0 ^P

110

126 (3.0)

15.5

110

18.0 ²

125

145 (2.25)

25.8

125

25.0 ^P

150

175 (3.0)

38.0

150

36 ^IEC

170

195 (3.0)

34.5 ^P

200

230 (3.0)

38.0

200

46.0 ^P

105

250

290 (3.0)

² ANSI / IEEE C57.12.00 = Distribution Transformers
^PANSI / IEEE C57.19.01 = Outdoor Power Transformers
^IECIEC 137

ANSI / IEEE C37.20.2 & 3

Electrolytic copper is standard in all Polycast bushings.
Cast copper, aluminum or forged aluminum options are also available for some items.

Tin plating is standard for all transformer bushings, silver is optional
Silver plating is standard for all switchgear bushings, tin is optional.

Indoor Bushings: Ambient -40C to +55C
Outdoor Bushings: Ambient -50C to +55C
Transformer Bushings: Oil Temperatures to 100C
These ambient temperatures are considered safe for all bushing applications. The various epoxy systems used by Polycast in bushing design have continuous operating temperature capabilities ranging from 120C to
180C, and all of these systems are capable of even higher temperature withstands on an intermittent basis.
Please consult catalog pages for recommended maximum continuous operating temperatures or contact Polycast for any special requirements.

Polycast designs and manufactures a wide range of bushings for transformer, switchgear and
other power applications to meet North American and International Standards. IEC 137 is used as a technical guideline, but ANSI and CSA specifications for specific types of bushings are always considered.