Delta 4000 Instruction Manual download pdf (Page 91)

Delta 4310 User Interface

81331 Rev 01 Nov 2010

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.

Bushing Hot Collar Tests

Hot collar tests are generally performed on HV bushings that do not have test

taps. However, these tests may also be done as an additional test if the bushings

have test taps

Tests 41 to 60 - These tests measure the outer shell insulation of the bushings,

including surface leakage and leakage current from the bushing surface through

the insulating material to the center conductor. A conductive strap is placed

around the bushing, below one of the skirts, normally the top skirt, and

connected to the HV lead. The Red lead is connected to the bushing conductor.

Test mode GST-GND is automatically programmed by the test form.

Multiple hot collar tests can be performed on each bushing. For each test, the

location of the strap should be clearly indicated on the form in the Designation

column.

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.

Tests 61 to 72 are measurements of the arrester insulation. Only test voltage,

current and watts are recorded for arresters. The HV lead is attached to the

arrester HV terminal. No connection using the Red or Blue leads is necessary.

The Test Mode used is GST-GND. Once the HV lead is connected, right-click

on the blue highlighted field on the desired test line to initiate the test sequence.

Follow the onscreen instructions to complete the test.

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Delta 4000 Instruction Manual Page 91