Application – All Motors
Transformer Capacity - Single-Phase or Three-Phase
Distribution transformers must be adequately sized to satisfy the kVA requirements of the submersible motor. When transformers are too small to supply the load, there is a reduction in voltage to the motor.
Table 4 references the motor horsepower rating, single- phase and
the smallest transformer required for open or closed
Other loads would add directly to the kVA sizing requirements of the transformer bank.
Table 4 Transformer Capacity
MOTOR RATING
HP | KW |
1.51.1
21.5
32.2
5 | 3.7 |
7.55.5
10 | 7.5 |
15 | 11 |
20 | 15 |
25 | 18.5 |
30 | 22 |
40 | 30 |
50 | 37 |
60 | 45 |
75 | 55 |
100 | 75 |
125 | 90 |
150 | 110 |
175130
200150
TOTAL | SMALLEST KVA | ||
EFFECTIVE | OPEN WYE | CLOSED | |
KVA | OR DELTA | WYE OR DELTA | |
REQUIRED | 2- TRANSFORMERS | 3- TRANSFORMERS | |
3 |
| 1 |
|
2 |
| ||
4 | 2 | 1.5 |
|
5 | 3 | 2 |
|
7.5 | 5 | 3 |
|
|
|
|
|
10 | 7.5 | 5 |
|
15 | 10 | 5 |
|
20 | 15 | 7.5 |
|
25 | 15 | 10 |
|
30 | 20 | 10 |
|
|
|
|
|
40 | 25 | 15 |
|
50 | 30 | 20 |
|
60 | 35 | 20 |
|
75 | 40 | 25 |
|
90 | 50 | 30 |
|
|
|
|
|
120 | 65 | 40 |
|
150 | 85 | 50 |
|
175 | 100 | 60 |
|
200 | 115 | 70 |
|
230 | 130 | 75 |
|
|
|
|
|
NOTE: Standard kVA ratings are shown. If power company experience and practice allows transformer loading higher than standard, higher loading values may be used to meet total effective kVA required, provided correct voltage and balance is maintained.
Effects of Torque
During starting of a submersible pump, the torque developed by the motor must be supported through the pump, delivery pipe or other supports. Most pumps rotate in the direction which causes unscrewing torque on
To safely withstand maximum unscrewing torques with a minimum safety factor of 1.5, tightening all theaded joints to at least 10
Table 4A Torque Required (Examples)
MOTOR RATING
HP | KW |
1 hp & Less | 0.75 kW & Less |
20 hp | 15 kW |
75 hp | 55 kW |
200 hp | 150 kW |
MINIMUM SAFE
10
2000
4