Dielectric Strength; Special/Design Tests; Insulation Power Factor(Tan Δ); Insulation Resistance - DAELIM GREEN EP TECH Operation & Maintenance Manual

Single phase & three phase pad-mount liquid compartmental transformer

Table of Contents

operation.Impedancevoltageisusuallyexpressedinperunitorinpercentoftheratedvoltageofthewinding

across which the voltage is applied and measured

Dielectric Strength

The dielectric test of the transformer is intended to check the ability of main insulation to earth, inter turn and

line end insulation to earth. It is generally performed in two different steps, likewise, Separate applied voltage

withstand test (Hi-Pot) and induced voltage withstand test

Insulation Power Factor (Tan δ)

The insulation power factor is the ratio of the power dissipated in the insulation in watts to the product of

The effective voltage and current in volt-amperes when tested under a sinusoidal voltage and prescribed

Conditions.

Insulation resistance tests are made to determine the insulation resistance from individual windings to ground

or between individual windings. Insulation resistance tests are commonly measured in mega ohms or may be

calculated from measurements of applied voltage and leakage current.

Atemperature-rise test isdefined asa testto determinethetemperaturerise above ambientofoneormore

ofthetransformer'swindings,asmeasuredattheterminals.Theresultforagiventerminalpairorwindingis

the average value of the temperature of the entire circuit; it is not the temperature at any given point in a

specificwinding.Thetermaveragetemperaturerisereferstothevaluedeterminedbymeasurementsona

given terminal pair of the winding. It does not refer to the arithmetic average of results determined from

different terminal pairs of the transformer

Lightning impulse tests shall consist of and be applied in the following order: one reduced full wave, two

chopped waves, and one full wave. The time interval between applications of the last chopped wave and the

final full wave should be minimized without intentional delays, to avoid recovery of dielectric strength if a

failure were to occur prior to the final full wave. Impulse tests shall be made without excitation.

Please refer to IEEE Standard C57.98-2011.

No.4 Business Building-2707, China Central Place

Chaoyang District, Beijing-100021, China

北京大林绿源环保科技有限公司

BEIJING DAELIM GREEN EP TECH CO., LTD.

Email:info@daelim-electric.com

Table of Contents