List Of Mandatory Tests For Transformers

The following routine tests specified in IEC726 shall be carried out at the manufacturer’s works on each and every transformer:

a) Measurement of winding resistance

b) Measurement of voltage ratio and check of vector relationship

c) Measurement of impedance voltage (principal tapping), short circuit Impedance and load loss

d) Measurement of no-load loss and current

e) Separate source voltage withstand tests

f) Induced over voltage withstand tests

g) Partial discharge measurement (below 10 pC at measurement as per IEC 726)

Type Tests For Transformers

One transformer of each rating and voltage ratio shall be subject to the following tests as per IEC 726.

a) Lightning impulse test

b) Temperature rise test

c) Measurement of sound level

All costs for conducting the above tests shall be included by the contractor in the price or can be charged separately as agreed.

Test reports for climatic tests and environment tests on cast resin transformers as per HD 464 S1 shall be submitted.

Optional Additional Accessories can be provided with transformers as under:

• 4 bi-directional rollers
• 2 lifting lugs
• 1 earthing terminal
• 1 aluminum rating plate
• 1 set of 3 PT 100 sensors
• 1 digital thermometer
• HV/LV cable boxes

Schedule of Transformers Can be prepared as per below example:

1500kVA,11Kv/433V CAST RESIN TRANSFORMERS

SR.NO	DESCRIPTION	REQUIRED	OFFERED
1.	Continuous rating at site conditions	-1500kVA
2	Normal voltage ratio at normal tapping at full load 0.8pf	11kV/415V
3.	Normal voltage ratio at no load	11Kv/433V
4.	System highest voltage	12kV
5.	Vector group	Dyn11
6.	Material of windings HV LV	COPPER/AL
7.	Class of insulation (HV/LV)	F
8.	Permissible winding temperature rise by resistance at normal loading  under 50 degrees ambient HV LV	90K 90K
9.	Impedance voltage	6.5
10.	Power frequency withstand voltage (kV RMS)	38
11	Impulse withstand voltage	95
12.	Maximum partial discharge when measured as per IEC 726	10 pC
13.	No load loss at normal voltage and tapping (max)
14	Load loss at normal voltage and tapping (max)
15	Preset level of temperature monitoring system. Alarm trip	150 degrees 160 degrees
16	Enclosure-degree of protection	IP31