Construction of Electrodynamic Power Factor MeterPoints : Construction of Electrodynamic Power Factor MeterThe instrument has a stationary coil which is divided into two
sections F2 and F1. Being connected in series
with the supply line, it carries the load current. Obviously, the
uniform field produced by F2 and F1 is
proportional to the line current. In this field are situated two
moving coils C1 and C2 rigidly attached to
each other and mounted on the same shaft or spindle. The two moving
coils are voltage coils but C1 has a series resistance
“R” whereas C2 has a series inductance “L”. The values of
R and L as well s turns on C1 and C2 are so
adjusted that the ampere-turns of C1 and C2
are exactly equal. However, I1 is in phase with the
supply voltage “V” whereas I2 lags behind V by nearly
90°. As mentioned earlier, there is no control torque acting on
C1 and C2 — the current being led into them by
the fine ligaments which exert no control torque.
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