19
IOM Manual: IOM-0000-CST IOM
Series CST: Submersible Turbine
01/01/2018 - Edition 1A
www.cps-pumps.com
Insulation resistance does not vary with rating. All motors of all
HP, voltage and phase rating have the same insulation resis-
tance ranges.
CONDITION OF MOTORS AND LEADS
OHMS
MEGOHMS
METER READING
R x 100K
or
R x 100,000
scale
R x 10K
orR x 10,000
scale
BENCH TESTS
• A new motor (without drop cable)
• A used motor which can be reinstalled in the
well
• Cable splice after immersion for one hour in
water
20,000,000+
10,000,000+
2,000,000+
20+
10+
2+
200+
100+
20+
2000 + or 2K +
1000 + or 1K +
200+
WELL TESTS (ohm readings are for drop cable
plus motor)
• A new motor or used motor in good condition.
• A motor in reasonably good condition.
• A motor which may have been damaged by
lightning or with damaged leads. Do not pull the
pump for this reason.
• A motor which definitely has been damaged
or with damaged cable. The pump should be
pulled and repairs made to the cable or the motor
replaced. The motor will not fail for this reason
alone, but will probably not operate for long.
• A motor which has failed or with completely
destroyed cable insulation. The pump must
be pulled and the cable repaired or the motor
replaced.
2,000,000 +
500,000-2,000,000
20,000-500,000
10,000-20,000
less than 10,000
2+
0.5-2.0
0.02-0.5
0.01-0.02
0-0.01
20+
5-20
0.2-5
0.1-0.2
0-0.1
200+
50-200
2-50
1-2
0-1
+ Indicates that the reading should be the value shown or
greater. Higher readings indicate better insulation.
FIGURE 5 – Nominal Insulation Resistance Values Between
All Legs & Ground
