X. Troubleshooting of Submersible Motors
1. Motor does not start but does not blow fuses or relay.
• No Power Supply → Replace fuses, breakers or check for loose or corroded connections and
motor lead terminals.
• Defective Connections → Correct connections.
2. Fuses or relay blow when motor starts.
• Incorrect Voltage → Apply correct voltage.
Voltage must be ±10% of rated (Nameplate).
• Incorrect Fuses or Relay → Replace with proper fuses and relay.
• Defective Capacitors → Replace with proper capacitors.
• Wrong Connections → Correct wrong connections or short circuit.
• Locked Rotor Conditions → Correct pump or well conditions.
• Insulation Resistance Down → Check the line and correct.
3. Motor runs for a while and then blows fuses or relay.
• Low Voltage or High Voltage → Apply rated voltage.
• Defective Capacitors → Replace with proper capacitors.
• Different Control Box for the Motor → Replace with proper control box.
• Defective Starting Voltage Relay → Replace with proper relay.
• Pump is Sand Clogged → Pull pump and clean well.
• Overheated Protector → Shield the control box from heat source.
The following conditions are stated to provide the owner with a list of criteria for maximum
motor life and to assure motor warranty.
IX. Motor Cooling, Temperature Ratings
Six (6) inch to (8) inch canned design motors from 5 – 150 hp will operate in water
up to 95º F (35º C), without any de-rating of horsepower, with a minimum flow rate
of .5 ft./sec. past the motor.
Table 10 — Minimum Flow Rates For Proper Motor Cooling
Well or Sleeve
Diameter
(inches)
6
7
8
10
12
14
16
Multiply gpm by .2271 for m
Multiply gpm by 3.785 for l/min.
FM Series Motors Installation, Operation and Maintenance Manual
Troubleshooting of Submersible Motors, Motor Cooling, Temperature Ratings
FM = 5.43" Dia.
6" FM Motor
0.5'/sec.
GPM Required
9
25
45
90
140
200
280
3
/Hr.
FM = 7.70" Dia.
8" FM Motor
0.5'/sec.
—
—
10
55
110
170
245
FLOW SLEEVE
15