Transformer Winding Temperature Indicator

OK, Varatharajankyr,

Is this for testing purpose on <10 systems (for example, some short, single time measurements for safety UL/CSA/CE certification)? Or, is the temperature monitor for continuous use in a system (for example: alarm, safety monitor, control input). What quantity?

www.omega.com for the omega engineering company is always a great place to start for temperature (pressure/flow/etc, too) monitoring components and systems. Get their handbooks or check them out online (will save a lot of trees). I'm sure they have application engineers to help out.

Hugh

Dear Vartharajankvr,

The standard method is to measure very accurately winding resistance R1 at some temperature T1 and, after heating, R2 at T2. Any signal or ac should be removed for this measurement.

Temperature rise T21 is calculated from :

R2 = R1(1+aT21), where a= temperature coeff of copper ( for copper winding)

You probably know this method, in that case was there any difficulty?

Ashok Dhingra

Hello varatharajankvr

Regarding power transformers, I suggest you look in the standard from IEC

IEC 76-2 or "same" from Cenelec EN 60076-2

Kind Regards

NB: To High temperature causes aging problem for the insulation system

Be careful, measuring the winding resistance gives an accurate on the average temperature. The actual temperature at the center of the windings may be 20 C higher, depending on configuration.

If you can imbed a thermistor at or near the hot spot, you will get a very accurate reading. Thermistors can be very small (say .25 mm (.010 in) diameter. However they are fragile until mounted (use a microscope). Maybe place one in the laminations next to the hot spot.

Browse http://www.gesensing.com/thermometricsproducts/

You can easily measure Winding Temp of the Power Transformer with help of WINDING TEMPERATURE INDICATOR, logon to www.scientificcontrols.com

you will find the product that will solve your problem

As i said earlier you can use Winding Temperature Indicator.

Now your query is How to measure?

--As per the Transformer rating calculate the difference you want in between Top Oil Temperature & Winding Temperature.

-- Then derive the Ring type C.T Ratio

For e.g : If you have derived that you want the Difference of 15 Deg C in btween Top Oil Temperature & Winding Temperature, and the Ring type C.T Ratio is 2000(rating)/ 5A (is resistance current that will pass through the rain type CT)

then you should inform the Winding Temperature Indicator manufacturer that the you want Winding Temp Indicator with Gradient 5A at 15 Deg C.

This will solve your problem

Vishal Shah

Dear sir

we are required Oil & winding temperatureindicator for 20 MVA Transformer

Dear Guest,

kindly log on to our website www.scientificcontrols.com for your requirment for OTI & WTI.

With Warm Regards