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In the power transformer we usually use the tap changer in 5 steps (-5, -2.5, 0, +2.5, +5) on primary side at off load.

the question:
1- why it is 5 steps?
2- why it is in the primary side? if it is on secondary side, is true?
3- why it is at off load?

thankyou very much

2007-12-03 01:09:37 · 4 answers · asked by AtheelKK 1 in Science & Mathematics Engineering

4 answers

The taps are each 2½% apart from one another. When the middle position is considered zero, these are generally referred to as "straddle taps" because the taps straddle the nominal voltage position.

1) Being able to adjust the voltage ±5% in 2½% increments is generally sufficient to meet the desired voltage. There are 7 position tap switches available, however the 5 position version is the most common.

2) The tap switch basically adds or removes turns from the primary winding. If the switch was connected to the secondary winding, the leads and the switch contacts would have to be MUCH larger.

3) The switch contacts are not designed to make or break load. Technically this is a De-Energized Tap Switch. If you move the tap switch while it is energized (but without any load) you will still damage the contacts. Down the road you'll likely have a tap switch hot-spot and ultimately a failure.

2007-12-03 02:36:22 · answer #1 · answered by Thomas C 6 · 2 0

The 5 steps has become an accepted standard but it basically allows for the steps to be small enough to keep equipment within acceptable variations of its design voltage and 5 covers sufficient variations in the supply. Most transformers are made to order and different configurations can be specified.

Its on the primary because the current is less at this point so cheaper to make.

They are not always "off load". If they are then it has saved money because an "on load' tap changer would be more expensive. Usually, "on load" is not required as the thing is set during install then very rarely, if at all, changed. Someone with large fluctuations may choose an "on load" tap changer and this may well be automatic to match changes.

2007-12-03 05:49:50 · answer #2 · answered by Poor one 6 · 0 0

1-It has to be 5 steps, to give enough allowance for voltage increase or reduction in the secondary.
2-Tap changers are on the primary side as standard manufacturer's practice, conductors going to the tap changer contacts are smaller than if it were in the secondary.
3-Tap changing has to be done off load for safety reasons. The undesirable voltage level at the secondary may affect the performance of the connected load. Besides, sparks may occur inside the transformer when tap changing with load.

2007-12-03 02:00:10 · answer #3 · answered by Anonymous · 0 1

From the voltage score it form of feels you will use this transformer for steping up after a generator. to avert any electric twist of destiny throughout the time of faucet changing technique, to boot to a on load faucet changer unit, we additionally strongly advised to apply a distant faucet changer panel particularly of working a sixty 3 MVA means transformer from its community OLTC.

2016-12-30 10:39:48 · answer #4 · answered by abrew 4 · 0 0

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