Gorman-Rupp Pumps S3B65-E6 460/3 861279 thru 1217130 - Manual (Page 39)

OM−04410 CONTROL BOXES
TROUBLESHOOTING PAGE D − 2
ELECTRICAL TESTING
Be certain to refer to the wiring diagram(s)
in the Installation Section of this manual be-
fore reconnecting any electrical compo-
nents which have been disconnected.
Test Equipment
A volt/amp/ohmmeter and megohmeter of ade-
quate range and quality will be required to conduct
the electrical tests. The suggested equipment indi-
cated below is commercially available, or an equiv-
alent substitute may be used.
Equipment Use
Ammeter/
Voltmeter To check AC Voltage
and current (amperage)
Ohmmeter To measure resistance
(ohms) to ground
Voltage Imbalance
Each phase of the incoming three-phase power
must be balanced with the other two as accurately
as a commercial voltmeter will read. If the phases
are out of balance, contact your power company
and request that they correct the condition.
Capacitors
The start capacitor is designed to split the electrical
phase during the initial power surge at motor start-
up. The start capacitor is controlled by the start
relay at motor startup. When the motor reaches
load speed, the start re;lay cuts out and permits the
run capacitor to maintain operation. Both the start
and run capacitors are located in the control box.
Before disconnecting the capacitor leads,
discharge the capacitors; use a screwdriv-
er with an insulated handle, and place the
blade across the two terminals of each ca-
pacitor to short the terminals.
Zero-balance the ohmmeter set to read RX100K,
and test the capacitors as follows:
a. Disconnect the capacitor leads, and remove
the resistor from the start capacitor.
b. Place a test lead against each of the termi-
nals of the start capacitor for a few seconds.
If the ohmmeter needle moves toward zero
then slowly drifts back to the left, the capaci-
tor is good. If the needle remains at infinity
(
∞) the capacitor is open; if the needle re-
mains at zero, the capacitor is shorted. In ei-
ther case, the capacitor must be replaced.
c. Test the run capacitor as in b. In addition,
test the metal run capacitor for shorts to
ground by touching one test lead to the ca-
pacitor case and the other lead to each of
the capacitor terminals in turn. The ohmme-
ter should read infinity (
∞); if it does not, the
capacitor is grounded and must be re-
placed.
Start Relay
The start relay is located in the control box.
Disconnect the two wires from relay terminal 2. Use
a zero-balanced ohmmeter set to read RX100K,
and touch one lead to relay terminal 2 and the other
to relay terminal 5. The resistance reading should
be between 4000 to 6000 ohms; if the reading is
not in this range, the start relay is defective and
should be replaced.
NOTE
Repair of individual electrical components is not
recommended. Replace defective and/or malfunc-
tioning components.