Delta 4000 Instruction Manual download pdf (Page 85)

Delta 4310 User Interface

81331 Rev 01 Nov 2010

NOTE Exciting current measurements are pending voltage level. Make sure use

same voltage level as in earlier measurements on same transformer.

Exciting current may also vary due to core magnetization status, exciting

current measurements should be performed prior winding resistance

measurement or after demagnetization.

Ratio Tests

Measurements of transformer winding ratio can be made with a high voltage

power factor test set when a TTR capacitor is available. Depending on the

voltage rating of the winding being energized, tests can be made up to 10kV.

The significance of this is that higher volts per turn can be applied to the

winding, stressing the winding turn-to-turn insulation more than low voltage

ratio test sets. This may be able to detect high resistance turn faults that may be

undetectable at lower voltage. The tests are performed one phase at a time on

three-phase transformers.

To enable this portion of the test form, select the Show TTR Tests checkbox at

the top of Page 1. A table for ratio test results will become visible near the end

of the form. You should select the Number of Tests based on how many

transformer taps you intend to test.

The first test must measure the capacitance of the Standard Capacitor, in pico-

Farads (pF).

Connect the test set leads, the HV lead and the Red measurement lead, directly

to the capacitor.

Initiate the test by right clicking on the blue field for the Standard Capacitor.

Subsequent tests require the HV lead to be connected to one side of a HV

winding (e.g. H1/U/A) where the other side of the HV winding is grounded to

the tank (e.g. H0/N/N). The corresponding winding on LV side is grounded on

one side and on the other side is connected to Red lead via the capacitor.

By enter the winding voltage levels in the form, the assessment is automatic.

Multiple Quick Tests

Standards measurements may be complemented with additional measurements

executed from the Multiple Quick Test sub-form selected as a new test or as

manual measurements in the standard test forms. Check “Manual” in the select

test boxes and a Multiple Quick Test table will be added at the end of the form.

In the field "INSULATION TESTED" you enter information on what to be

tested, TEST MODE set/change the test mode, SUPPRESS set/change noise

suppression mode.

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Delta 4000 Instruction Manual Page 85