Answer / shane e.

It is the ratios of of insulation resitance on a DC hi-pot test over 10 minutes. If less than 1 insulation is surely breaking down.

Answer / lovy

Polarization index is an indirect method of testing which may mislead about healthiness of transformer insulation
so instead of pi , capacitance and tan delta should be measured for keeping a correct check on insulation

Answer / josephat murusura

PI is the ratio of the 10minutes megger value to that of
the 1 minute.The minimum acceptable value is 2.Any value
below 2 is not good enough for the operation of the
electrical machine[motor or transformer]& it indicates that
the winding insulation has detoriated.

Answer / karthik

It's minimum acceptabce value depends on the class of
insulation also. Minimum recommended value IR(60 sec)/IR(15
sec) should be 1.3 for all classes of insulation.

Answer / sandipan sarkar

it is ratio of insulation resistance (IR)for 10 minutes to
insulation resistance for 1 minute.

it should be 2.5

For the same power rating,which motor is bigger in size,AC or DC?

9 Answers   Bhel,

what is the power factor of an inductive load ? (i) Zero (ii) Lagging (iii) Leading (iv) Unity

5 Answers  

If single phase having 220v so why 3phase is440v.

7 Answers   DLF,

Multimeter show phase to neutral volt 230 the per phase but phase to phase 415 not show 460 why.

1 Answers   Intas,

I am getting above 60 V as open delta voltage against single phase unit ICT at tertiary delta formed and ICT getting trippped on NDR. ICT tested and found in order. PTs provided on tertiary are tested and in order. what may be the reason?

0 Answers  

How much should be the specific gravity of a DG set battery Electrolyte.

2 Answers  

what is the operation of regulator in fan?

4 Answers   NTPC,

Why lightning arrester blast in rainy day?

1 Answers   Eco Cement, Mahaveer, MBDL,

in dc machines in the armature nature of power is ac but why we take rasistance instead of impedance?

1 Answers  

how to calculate earth resistat in earthpit with earth testing kit?

2 Answers  

Why i receive the GCU fault in my DG Sychronization panel . what all the factors considered for this fault .

0 Answers  

Can anyone provide with a SLD for HT panel installation for a 33KV line and distribution end has three 1.5MV transformers. Is it suitable to use OCB or VCB and also provide me the suitable rating and its connection diagram.

0 Answers   TATA,