Withstand (Proof) Tests; Example Of Electrode Gap Selection Screen; Example Of Display For Starting Bs 5730A Proof Test - Megger OTS 60PB Guide De L'utilisateur

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Operation
The three soft keys now assume different functions. If desired press the left hand key labelled 'VIEW'
to bring back into view, sequentially, the breakdown voltage values of each individual test and the
average value in turn.
Press the 'NEW' key to return to the start of the selected test sequence. Press the left hand 'START'
key to repeat a test sequence or the 'MENU' key to return to the main menu.
Note:–
At any time during a test sequence the right hand control key, labelled 'STOP', can be used to
end a test and return to the initial test screen.

Withstand (Proof) Tests

There are four types of withstand (proof) test available, BS 5730a, BS 5730a LEPLC and Withstand (Proof)
Tests A and B. They enable the oil sample to be subjected to a known withstand voltage for one minute,
to see if breakdown occurs. Withstand Test A causes the voltage to rise to a set value, remain there for
one minute and then be removed (if breakdown does not occur beforehand). Withstand Test B causes the
voltage to rise to a set value, remain for one minute and then be further increased to maximum or the
breakdown point whichever occurs sooner.
Automatic proof testing according to specification BS 5730a
The actual number of tests performed is dependent on individual test results with the maximum number
being three. Proof voltage limits are prescribed within the specification and are dependent on the
installation category of the equipment from which the oil sample was removed and also the electrode
spacing within the oil test set. The basic sequence of events for this test are; the test voltage is ramped up
to the internally selected upper voltage limit and held at this limit for a period of one minute. After this period
the test voltage is removed and the test considered a pass. Should a breakdown occur at any point during
the test, two further tests must be performed with stand and stir times between. Both tests must be
successful for the sample to be passed. A failure of the second test will terminate the sequence, as a pass
is no longer possible.
BS 5730a (Automatic Withstand (Proof) Testing)
1.
From the main menu select 'BS 5730a' option. The screen then prompts for the 'EQUIPMENT
CATEGORY'. Reference should be made to BS 5730a specification for further information. Category
selection is made using the control keys. A, D selected using left key and B, C, E, F using the centre
key. Use of the right hand key reverts the user to the main menu.
2.
Pressing the left hand key labelled A, D generates the screen shown in figure 11. Use the left and
centre control keys to select the programme for the desired electrode gap. This gap should have
been previously set according to the BS 5730a test required.
3.
Assuming the 2,5 mm key was operated, the display will now change to that shown in figure 124.
The correct proof voltage and the electrode gap information will be displayed, in this example
Withstand voltage = 30 kV with a 2,5 mm gap. To start the test operate the left key. Use of the right
hand key reverts the user to the main menu.
SELECT GAP
BS 5730a : A, D
2,5 mm
Figure 11

Example of electrode gap selection screen

? mm
4,0 mm
QUIT
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