Tranformer 1500KVA 11KV/415V

A1) 1600kVA.

A2) It depends on ambient temperature. If it isn't in the User Manual supplied with it, ring the manufacturer and ask.

I think you are from India.

How is that you are keeping the oil Cooled transformer inside the Hall. Oil cooled transformers are meant to be kept outside, safety point of view. Local Electrical regulations does not permit to keep the oil cooled transformers to keep inside.

If the Transformer is rated for 1600 kVA, it can be loaded 100%.

Oil cooled transformers are working in indoor enclosures(room)with adequate fire protection measures. In open areas(hall) silicon oil filled transformers were used.

Dear Mr. ramvinod,

I fully agree with you. Also I want to supplement to your answer. If cooling aspect is taken due care - by providing additional cooling, the Transformer can be loaded to the extent - which does NOT allow INCREASE IN OIL TEMPERATURE, beyond the permissible limit.

DHAYANANDHAN.

Hi Ramvinod ,

There seems a small correction transformers above 11 kV are normally installed out door.

There are both indoor type and outdoor type oil cooled 11/ 0.44 kV transformers available . The indoor type Oil cooled transformers can be installed at indoor substations and production plants with safety provisions specified . They have to be installed as per IE rules 1956 chapter VII clause 64 provides detailed provisions regarding installing oil filled transformers indoor with sock pit provisions. substations having transformers beyond 2000 liters of oil cannot be fitted in basement

b (ii)provisions of sock pit .....

(iii) "Oil Filled transformers installed in doors shall not be on any floor above the ground or below the the first basement "

Dear sir

Thanks for correction.

Dear Ramvinod,

You are welcome. I knew it was only a slip in writing and not intentional mistake so corrected it and knew you will take it in good spirit.

As per Indian Standard IS:2026, the allowable maximum temperature rise of winding ( measured by resistance method) is limited to 55 deg C over an ambient of 40 deg C. The max. temperature rise of oil ( measured by thermometer)is limited to 50 deg C. If you keep a margin of 5 deg C then temperature setting for tripping of circuit breaker may be considered as 90 deg C for winding and 85 deg C for oil of ONAN ( Oil Natural Air Natural) transformer.

Oil filled transformers are not recommended inside switchgear rooms due to fire hazard. However, they may be installed in transformer cells with barrier walls and front opening construction with expanded metal fencing. Silicone oil insulated (non-inflamable) transformers may be installed indoors as suggested by Pnaban. Dry type or cast resin transformers may also be used for indoor application.

As advised by DEBATA07, please set the temperature to trip on High Oil Temperature.

Hi Winding temperature may not be available on such a small transformer as it needs CT and image coil.

You have transformer installed indoor in ventilated room, to avoid any risk of failure and fire, better use the high oil temperature trip that over current trip.

The Margin between Max permissible temperature of winding (90 Deg C for Class Y insulation) and oil shall be minimum 10 Deg C. That means you should set High Temperature Trip at 80 Deg C. (general industrial practice of difference between max. hot spot temperature and trip temperature on average temperature of oil on top of tank).

The Temperature trip shall be through Manually Reset Auxiliary Relay for following reasons:

1. The Contact type temperature gauge contact rating is usually not sufficient to take current of trip coil of CB. (A CB with under voltage trip coil shall be more safe or fail safe option).

2. Once the high temperature trip has occurred, one can not energise it without resetting the relay - knows he is doing a blunder without checking the reason.

If you have annunciator panel and dual contact temperature gauge then the second contact can be set at 75 Deg C to give warning alarm.

Many had suggested that the transformer is indoor. They are right it is a fire risk, but I have seen such installations in Delhi in old high rise buildings in Connaught Place. People do not relocate these or replace with Dry Transformers with Class G insulation (which will char but won't support flame) and are sitting on future inferno.

It must be silicon oil filled transformer as it has been mentioned it is in door transformer. It can be loaded up to rated full load current of the transformer continuously.Manufacturer should be contacted for temp setting.Loading can be increased based on temp of the transformer for short time as per the requirement.

Apart from using the Manufacturer's manual and the data on the name plate of the transformer, and the sound advice of debata07, check out website http://www.3phasepower/3phasetransformers.htm and you will get to know about almost all types of transformers, how to size them, how to calculate load current, voltage, kVA rating etc. I hope that this helps.

Kirloskar transformers are good quality products and I have visited their production units and conducted type test and routine test at their lab when we purchased them They have test facilities and conduct as per standards. So you can very well load them as per their rating and temperature rise they specify. I have been using them for more than 20 years and are still functioning properly because our protective systems were well designed and maintained properly. I have even loaded them beyond their rated capacity for short durations during emergencies and found to work with out any abnormal temperature rise.

I believe that OP is not asking your CV.

Thanks for the comment. It will be better if make your comment with an address and not as an anonymous Person. From your comment I can understand what is your age.

Any way I do not have to give my CV to you to get a job. It is only to give assurance to PO the quality of the Kirloskar make Transformers and their reputation .