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From the supply line on a typical 230 volt circuit, a 115 volt
potential exists from the "R" terminal to ground through a
possible short in the capacitor. However, from the "S" or
start terminal, a much higher potential, possibly as high as
400 volts, exists because of the counter EMF generated
in the start winding. Therefore, the possibility of capacitor
failure is much greater when the identifi ed terminal is con-
nected to the “S" or start terminal. The identifi ed terminal
should always be connected to the supply line, or "R"
terminal, never to the "S" terminal.
When connected properly, a shorted or grounded run-
ning-capacitor will result in a direct short to ground from
the "R" terminal and will blow the line fuse. The motor
protector will protect the main winding from excessive
tem perature.
Capacitors
Many motor capacitors are internally fused. Shorting the
terminals will blow the fuse, ruin ing the capacitor. A 20,000
ohm 2 watt resistor can be used to discharge capacitors
safely. Remove wires from capacitor and place resistor
across terminals. When checking a dual capacitor with
a capacitor analyzer or ohmmeter, both sides must be
tested.
Capacitor Check With Capacitor Analyzer
The capacitor analyzer will show whether the capacitor is
"open" or "shorted." It will tell whether the capacitor is within
its microfarads rating and it will show whether the capacitor
is operating at the proper power-factor percentage. The
instrument will automatically discharge the capacitor when
the test switch is released
Capacitor Connections
The starting winding of a motor can be damaged by a
shorted and grounded running capacitor. This damage
usually can be avoided by proper connection of the running
capacitor terminals.
WARNING
HAZARD OF SHOCK AND ELECTROCUTION. A
CAPACITOR CAN HOLD A CHARGE FOR LONG
PERIODS OF TIME. A SERVICE TECHNICIAN WHO
TOUCHES THESE TERMINALS CAN BE INJURED.
NEVER DISCHARGE THE CAPACITOR BY SHORTING
ACROSS THE TERMINALS WITH A SCREWDRIVER.