2.3. Conductors 21
MOV size, and a wide range of diameters is available to handle nearly
any design need. Small units are supplied with wire leads, whereas the
larger units are packaged in molded cases with mounting feet and
screw terminals for connections.
Another device in the protection arsenal is the surge capacitor.
Transient voltages with fast rise times, high dv/dt, may not distribute
the voltage evenly among the turns on a transformer or motor wind-
ing. This effect arises because of the turn-to-turn and turn-to-ground
capacitance distributions in the winding, an effect described in Chap-
ter 7. Surge capacitors can be used to slow the dv/dt and minimize the
overvoltages on the winding ends. These are generally in the range of
0.5 to 1.0 µF ...