Answer / baikunth

As we know DC current is uni-directional.The deflection
system attached to the megger is generally PMMC type which
eorks only with DC. Another reason is when DC current flows
in the winding of a motor or transformer the capacitance and
inductance do not act upon the current and the only leakage
current that flows through the insulation is measured.This
gives faster and accurate measurement.If we use an AC megger
the reading will be erroneous because the capacitance of
winging will allow to flow high current and breakdown of
insulation will not occur due to alternating action of
current.

Answer / abaya

We can create voltage like 5kv,1kv,using DC but we can not produce that type of voltage using Ac because it require more space as compare to Megger.

Answer / k.prakashchandra

Further you maintain potential difference for a substantial
period,which is possible with DC

There are two nos of 33Kv/11Kv 5MVA transformers conecting through HT cable from substation having metering at substation itself.One transformer used at a time another remains stand by.Further 11 nos of 11Kv/440V transformers are attached on it and each transformer is having its own Power factor correction panel.Now one 33/11Kv transformer at no load condition/Stand by condition is having power factor in leading side upto 0.21 and while when another tranformer at same situation have power factor in lagging 0.42. Now one thing is clear that transformer one is having 1.5 Km long 33kv cable due to that PF goes in leading side and another is having only 250 mtr length remains him lagging. Now i want to know that how i can maintain the Power factor at no load/ stand by position though both are behaving in seperate manner.

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