motor. In addition, the maximum variation of any phase from the average value should not exceed one
percent. The effect of unbalanced supply voltage is to create a current unbalance and increased losses
in the motor far out of proportion to the magnitude of the voltage imbalance.
5.9 Electrical Cable
It is also important that the cable be tested both before and during the installation. To test the cable after
splice, connect one megger lead to the bowl assembly and the other lead to one of the cable leads at the
cable reel. Minimum reading should be 50 megohms. Wet down the motor cable, splice, and as much of
the cable as practical. The megger reading should be the same as before. If it reduces materially, there is
a leak somewhere and it should be found by wetting down the cable a portion at a time, taking megger
readings all the while. When testing the cable during installation, the cable should be megged every pipe
section as soon as the motor reaches water level. To do this, connect one megger lead to the cable reel
and the other lead to the discharge pipe. This will immediately indicate any cable damage during installa-
tion. Minimum reading should again be 50 megohms.
Since motor leads are marked for proper rotation, do not lose their indentity. Check each single conduc-
tor of the cable with a megger before completing the installation of each cable connector. Common con-
ductor ends are identified by low resistance reading of the megger. Mark each single conductor of the
cable as the motor leads are marked, or record color of each conductor before making connection to mo-
tor leads.
Depending upon the clearance in the well casing, depth and straightness of the well, there may be some
danger of pinching the cable between the column pipe coupling and well casing when lowering the unit. If
Goulds Pumps protector-type cable supports are not used, a rubber padding may be used to cover the
cable at these points if there is any danger of abrasion or pinching the cable. When lowering the unit, the
discharge pipe should be held against the casing on the side opposite to the cable to allow as much
clearance for the cable as possible.
Top of well casing may have sharp or rough edges and so it is important to protect the cable against cut-
ting or scraping at this point also. A protective covering may be clamped over the rough well casing or
the cable may be run over a pulley mounted high enough to allow the conductor to follow the discharge
pipe down during the installation. Padding made of gasket material or something similar could also be
used at the well head for protection.
5.10
Electrical Control Equipment
Starting switches will usually be of the type used, in connection with surface motors; however, attention
is drawn to the difference between submersible motors and surface motors as regards full load current
ratings. This must be taken into account when sizing protection devices. See overload allowables in fore-
going pages.
It is recommended that quick-trip relays unaffected by ambient temperatures at the surface be installed
to protect each of the three phases. For complete protection, fustrons may also be applied to each leg.
other controlling devices must depend on system design. This would include pressure switches and oth-
er such equipment. Additional protection should be provided to insure that the unit will not start or run
unless adequate submergence is provided.
In areas where electrical storms are prevalent, the use of lightning arresters (in the case of three phase
motors, two arresters) is excellent motor protection.
5.11 Airline Installation and Operation
An airline submerged in the well water provides the simplest method of determining the depth to the wa-
ter level. To use an airline, it is necessary to know the exact length of the line from a reference point,
5.9 Electrical Cable
20
VIS Installation, Operation and Maintenance Instructions
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