Delta 4000 Manuál s instrukcemi stáhnout pdf (Strana 82)

81331 Rev 01 Nov 2010

Bushing C2 Tests

Bushings with test taps may also be tested to obtain a C2 insulation

measurement. The C2 insulation is the insulation between the test tap

connection and the bushing mounting flange. To perform a C2 test, the HV lead

is carefully connected to the bushing test tap and the Red lead is connected to

the bushing center conductor. Care should be taken not to cause physical

damage to the test tap, as the tap connection point may be a small pin or a

flexible spring. If this is the case, use a small insulated jumper wire or a specially

designed test tap adapter to make the HV lead connection.

CAUTION

Bushing test taps have very limited insulation and should

generally be energized at reduced voltage levels. If the

bushing manufacturer does not specify a test voltage level

use no more than 500 volts (0.5kV).

Tests 20 to 27 are measurements of the individual bushings C2 insulation. All

are performed with test mode GSTg-R All phase and neutral bushings may be

tested providing they have test taps.

NOTE: Similar to the bushing C1 tests, all the C2 measurements may be made

with the bushing shorting leads still in place from the transformer overall

tests.

Surge Arresters

If the transformer is equipped with surge or lightning arresters, these may be

tested as well. If the arrester is a single-stack unit, its HV connection must be

disconnected to eliminate the measurement of losses from other connected

apparatus (such as switch and support insulators). Multi-stack arresters may be

tested without disconnecting if desired. The procedure described below assumes

single-stack arresters are being tested.

Nameplate, serial number and location information for each arrester should be

entered so that future testing can be compared to specific units.

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Delta 4000 Manuál s instrukcemi Strana 82