Construction of Electrodynamic Power Factor Meter

Construction of Electrodynamic Power Factor Meter Points : Construction of Electrodynamic Power Factor Meter The 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.