ABB BRIT-90-35-200 Manual de operação - Página 12

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ABB Power Grids Ltd.

Capacity C1 depends on the bushing temperature and increases by approximately 0.04% with an increase

in temperature of 1 ° C. The value of the capacity C1, related to 20 ° C:

= С

1,20°С

1 measured.*

10.3 Measuring equipment

10.3.1 Measuring bridge

To measure capacitance and tangents delta, use a measuring bridge (Schering bridge).

Examples of measuring bridges:

Table 4

Manufacturer

Doble Engineering Company, USA

Tettex Instruments, Switzerland

FGUP "NIIEMP", Penza, Russia

OOO NPO "Technoservice Electro", Moscow,

Russia

GNPP "Spetsavtomatika, Kiev, Ukraine

For the use of bridges, see the manufacturer's operation manual.

10.3.2 Power source

For measuring the capacitance and tgδ

or embedded in the measuring equipment.

10.4

Installation and connection of the bridge

Make sure that the transformer is off and out of service.

For safe and reduce influence of interference, short circuit all the transformer winding. Ground the winding

that are not connected to the bushing being tested.

Connect the measuring bridge to the test tap as required in the relevant operation manual.

Depending on which insulator is checked, connect the power source (test voltage) to the terminate plate or

the test tap.

Testing wires must be as short as possible and must not contact grounded objects.

The test tap must be clean and dry.

10.5

Measurement procedure

Connect the grounding terminal of the bridge to the transformer grounding terminal. The flange of the

bushing not installed on the transformer and to be measured must be grounded.

Before putting the bushing into service, carry out a measurement of dissipation factor tgδ

at the voltage up to 10 kV in order to have a reference for later checks.

On completion of measuring, remove the test adapter from the test tap and screw on the protective cover to

protect the test tap from moisture and contamination (in this case the test tap is grounded automatically).

The test tap must not be open during service or storage.

(1 – ΔТ

0,0004), where ΔТ = Т

use at least a 10 kV power source. The source may be independent

GKSL 680205.021 RE

Rev. 2, 26.09.2019

– 20°С

bushing

Model

M2H

2809

2816a

2820

Tangens 2000

Vektor-2.0 M

P-5026 M

CA7100-1, CA7100-2

and capacity C