Xylem VS Manual Del Usuario página 14

TABLE C.1 — NORMAL INSULATION RESISTANCE VALUES BETWEEN ALL LEGS AND
GROUND
Insulation resistance does not vary with rating. Motors of all HP , voltage and phase rating have the same insulation
resistance ranges.
CONDITION OF MOTORS
AND LEADS
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.
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.
+ Indicates that the reading should be the value shown or greater. Higher readings indicate better insulation.
Resistance measured between the power cable leads after
splicing the power cable to the motor leads will indicate
the resistance of the power cable plus the motor wind-
ings. The motor winding resistance is obtained by the
formula below. The calculated value should be within the
limits specified in the motor manual.
Motor Winding = Reading taken – Cable Resistance
Resistance at Power Cable
14
OHMS
20,000,000+
10,000,000+
2,000,000+
2,000,000+
500,000–
2,000,000
20,000–
500,000
10,000–
20,000
Less than
10,000
A higher winding resistance than shown in the motor
manual indicates a possible burned (open) winding, an
open cable, a loose connection or the wrong motor (dif-
ferent HP or voltage than readings being referenced).
A considerably lower winding resistance than shown in
the motor manual indicates a possible shorted (burned
together) winding or the wrong motor.
from Table 2.
Unequal resistance between the windings on a three
phase motor indicates a burned winding or a faulty con-
nection.
METER READING
R x 100K
MEGOHMS or
R x 100,000
Scale
20+ 200+
10+ 100+
2+ 20+
2+ 20+
0.5–2.0 5–20
0.02–0.5 0.2–5
0.01–0.02 0.1–0.2
0–0.01 0–0.1
R x 10K
or
R x 10,000
Scale
2000+ or 2K+
1000+ or 1K+
200+
200+
50–200
2–50
1–2
0–1