Submersible motor pumps (100 mm)
2
Now motor is ready for operation.
If a unit has been in storage for more than 2 months, check for
the motor filling and for rotor freeness.
2.2.2 Insulation resistance (IR)
The insulation resistance value of the new motor with 500 V DC
megger is generally 20 Mega Ohms. For older motors if the value
observed to be less than 2 Mega Ohms, please contact KSB or
Authorized Dealer before switching on the motor.
2.2.3 Extended Cable connection
Only the proper cable connector ensures a perfect watertight
joint and provides a protection against mechanical damage to
the cable jointing. While connecting extra cable beyond standard
length along with the pump set, it is necessary to have a water
tightened cable joint.
a. To connect the cables, cut off and strip the motor cable and
join it is staggered fashion where no 2 joints overlap each
other.
b. Colors of the leads, which are to be joined together must be
identical as per following sketch (Fig. 1).
c. Wrap vulcanizing rubber compound to each cable joint and
again wrap with electric insulation tape on the top of it.
d. To ensure proper insulation once again wrap with vulcanizing
rubber compound and electric insulation tape for each joint.
e. Finally wind the total cables with electric insulation tape.
f. Oil or grease should not have any contact with the tape.
g. Complete the taping over core insulation at each side.
Please see that each turn of the tape should have a 50% overlap
over the previous turn. The tape should be wound on to a
thickness at least equal to that of core insulation.
2.2.3.1 Selection of Cable
Voltage drop for extended cable should not be more than 3% of
rated voltage i.e.
Permissible voltage drop = Available voltage x 0.03
For Single phase :
Voltage drop = 2 x Cable Length in meters x Resistance / meter
for particular cable size x motor current
Allowed voltage drop is up to 7.0 volts (Considering available
voltage 230 volts).
e.g. For the cable length of 50 m and area of cross section 1.5
mm
2
, with rated current 3.5 A,
Voltage drop = 2 x 50 x 0.0121 x 3.5
= 4.24 volts (which is permissible)
For three phase :
Voltage drop = Cable Length in meters x Resistance / meter for
particular cable size x motor current
Allowed voltage drop is up to 12.5 volts (Considering available
voltage 415 volts).
e.g. For the cable length of 50 m and area of cross section 1.5
mm
2
, with rated current 2.4 A,
Voltage drop = 50 x 0.0121 x 2.4
= 1.45 volts (which is permissible)
Resistance / meter according to cross-section area :
Cross - section area Resistance in Ohm / m
(mm
2
) At 30
0
C
1.5 0.0124
2.5 0.0075
4.0 0.0047
6.0 0.0031
2.2.4 Coupling of pump and motor
Couple the shaft to motor in vertical manner.
Before fitting the suction strainer the effortless rotation of the
coupled rotor should be checked at the sleeve coupling.
Please ensure that the top face of sand guard presses the bottom
face of the sleeve coupling to avoid the entry of sand inside the
coupling.
Fig. no. 1
R = Red colored lead
Y = Yellow colored lead
B = Blue colored lead
Fig. no. 2
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