Xylem BMAID R4 - Manual (Page 35)

PAGE 35
Residential Water Systems
CentriPro
mEaSurING INSulatIoN rESIStaNCE
1. Set the scale lever to R x 100K (R x 100,000) and
set the ohmmeter on zero.
open (turn off) master breaker
or disconnect all leads from
starter or control box to avoid damage to
meter or electric shock hazard.
2. Connect an ohmmeter lead to any one of the
motor leads and the other to the metal drop
pipe. If the drop pipe is plastic, connect the
ohmmeter lead to the metal well casing or
ground wire.
WARNING
tablE 1 – Normal ohm and megohm Values (Insulation resistance) between all leads and Ground
Insulation resistance does not vary with rating. All motors of all HP, voltage and phase rating have similar values of insulation resistance.
Condition of motor and leads ohm Value megohm Value
A new motor (without drop cable). 20,000,000 (or more) 20.0
A used motor which can be reinstalled in the well. 10,000,000 (or more) 10.0
Motor in Well. Ohm readings are for drop cable plus motor. A new
2,000,000 (or more) 2.0
motor in the well.
A motor in the well in reasonably good condition. 500,000 - 2,000,000 0.5 - 2.0
A motor which may have been damaged by lightning or with damaged
20,000 - 500,000 0.02 - 0.5
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
10,000 - 20,000 0.01 - 0.02
replaced. The motor will not fail for this reason alone, but it will
probably not operate for long.
A motor which has failed or with completely destroyed cable insulation.
Less than 10,000 0 - 0.01
The pump must be pulled and the cable repaired or the motor replaced.
megger…
What It Means –
1. If the ohm value is normal, the motor windings
are not grounded and the cable insulation is not
damaged.
2. If the ohm value is below normal, either the
windings are grounded or the cable insulation
is damaged. Check the cable at the well seal as
the insulation is sometimes damaged by being
pinched.