Thanks all.
Palletjack , the ratio meter is a digital electronic one from Raytech. The markings are very clear.
There are two similar transformers.And this deviation in current is observed in only one transformer.
We measured the DC resistances too, but they are in order.
Dear RedSanke,
Thanks for pointing out that. Yes we changed the probe and still the error is in the same phase of transformer. So we are sure that the issue is not with ratio meter.
Dear All,
We are performing a transformer ratio test on a 1 MVA,33kV/400V transformer using a three phase transformer ration meter from a reputed manufacturer.The ratio meter is also showing the current (mA) in each phase in addition to the turns ratio value. During the testing, we found out...
Dear All,
We are looking to purchase some metal oxide surge arresters of rating 33kV, 10kA to be mounted on distribution transformers.
However, our consultant wants to use surge arresters of line discharge class 3 for this purpose. We tried to find this item with many surge arrester...
Hi Guys,
Please guide me for the following.
We are to provide neutral voltage displacement protection in a solar power plant. For this, a 3 phase protection VT is utilized.Primary winding of the VT is connected to 33kV lines in the power system.Primary winding is star connected and neutral is...
Dear All,
What shall be the acceptable tan delta values as power frequency and 20 degrees of Celsius for new small distribution transformers.
For larger power transformers there are specified maximum value of 0.5%. But when we are doing the testing in many number of small distribution...
Hi xnuke,Thanks.Yes I saw that excellent post by waross.But as per that explanation "grounding the wye point makes no difference UNLESS the source wye point is also grounded. Then the connection becomes a neutral connection that is incidentally grounded".
However , what was stated in IEEE...
Dear All,
We are having a transformer with a vector group Dyn11(low voltage primary connected in star with a neutral).This is to be used as a step up transformer in a Solar Generation System. The inverter output is having just 3 wires with no neutral.
We planed to connect the primary neutral of...
Dear All,
Is it permissible to use an oil type transformer inside a containerized substation with a control room inside where a operator will be there all 24 hours a day.The substation will be as per the attached image with a LV compartment, HV panel , a transformer and a control room.All...
Dear All,
Most of the transformer technical specifications are requesting for the value of thermal time constant from the manufacturers to specify. Is there any good or bad in thermal time constant being high or low , for a customer? Why this value is significant. Please advice.
We have got a requirement to measure the winding capacitances of a 4 MVA, 33kV/690V two winding transformer. But we have no idea on what values (of which range) to expect as results of this test or how to analyze the results of this test. I shall be much grateful if you could give us a...
