What is polarisation index value?.(pi value)
Simple & brief definition of polarisation index?..
Answer Posted / kapil mishra
PI is a variation of the IR test. It is the ratio of IR
measured after voltage has been applied for 10 minutes (R10)
to the IR measured after one minute (R1), i.e.
PI = R10/R1
Low value of PI indicates that the winding may have been
contaminated with oil, dirt etc or absorbed moistures. In
the test, a relatively high DC voltage is applied between
the copper conductor and the stator or rotor core usually
between the winding and ground as the machine core & body
are grounded)
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