A reciprocating compressor has a varying
torque requirement per revolution, depending on
number of cylinders, crank angle, etc. As discussed
previously, the angle of rotor lag and the amount of
stator current vary with torque. There will be a
cyclic pulsation of the load current during each
revolution. This in itself is not too objectionable,
but excessive current pulsation may result in
appreciable voltage variation and thus affect lights
or other devices sensitive to voltage change.