Wiring Checks And Installation; Startup; Startup With Three-Phase Motors; Check The Direction Of Rotation - Grundfos SP Instrucciones De Instalación Y Funcionamiento

6.6.6 Wiring checks and installation

Before making the final surface wiring
connection of the submersible drop cable to the
control box or control panel, it is a good practice
to check the insulation resistance to ensure that
the cable and splice are good.
Measurements for a new installation must be at
least 2,000,000 ohms. Do not start the pump if
the measurement is less than this.
If it is higher than 2,000,000 ohms, the
submersible drop cable should then be run
through the well seal by means of a conduit
connector in such a way as to eliminate any
possibility of foreign matter entering the well
casing.
Conduit should always be used from the pump
to the control box or control panel to protect the
submersible drop cable. See fig. 15.
Finish wiring and verify that all electrical
connections are made in accordance with the
wiring diagram.
Check to ensure the control box or control panel
and high-voltage surge arrester have been
grounded.

7. Startup

After the pump has been set into the well and
the wiring connections have been made, go
through the following procedures:
1. Attach a temporary horizontal length of pipe
with installed gate valve to the riser pipe.
2. Adjust the gate valve one-third of the way
open.
3. On three-phase units, check direction of
rotation and current imbalance according to
the instructions below. For single-phase
units proceed directly to
the well on page 16.
4. Under no circumstances should the pump be
operated for any prolonged period of time
with the discharge valve closed. This can
result in motor and pump damage due to
overheating. A properly sized relief valve
should be installed at the well head to
prevent the pump from running against a
closed valve.
7.1.3 Developing

7.1 Startup with three-phase motors

7.1.1 Check the direction of rotation

Three-phase motors can run in either direction
depending on how they are connected to the
power supply. When the three cable leads are
first connected to the power supply, there is a
50 % chance that the motor will run in the proper
direction. To make sure the motor is running in
the proper direction, carefully follow these
procedures:
1. Start the pump and check the water quantity
and pressure developed.
2. Stop the pump and interchange any two
leads.
3. Start the pump and again check the water
quantity and pressure.
4. Compare the results observed. The wire
connection which gave the highest pressure
and largest water quantity is the correct
connection.

7.1.2 Check for current imbalance

Current imbalance causes the motor to have
reduced starting torque, overload tripping,
excessive vibration and poor performance which
can result in early motor failure. It is very
important that current imbalance be checked in
all three-phase systems. Current imbalance
between the phases should not exceed 5 %
under normal operating conditions.
The supply power service should be verified to
see if it is a two- or three-transformer system.
If two transformers are present, the system is an
"open" delta or wye. If three transformers are
present, the system is true three-phase.
Make sure the transformer ratings in kilovolt
amps (KVA) is sufficient for the motor load.
See section 10.3 Transformer capacity
required for three-phase submersible motors
on page 25.
The percentage of current imbalance can be
calculated by means of the following formulas
and procedures:
Total of current values
measured on each leg
Average
=
current
Greatest amp
difference from the
% Current
=
imbalance
average current
3
average
X 100
15