Startup; Startup With Three-Phase Motors; Check The Direction Of Rotation; Check For Current Imbalance - Grundfos SP Serie Instrucciones De Instalación Y Operación

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.
4. Do not operate the pump with the outlet
valve closed. This can result in motor and
pump damage due to overheating. Install a
properly sized relief valve at the well head to
prevent the pump from running against a
closed valve.

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.
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7.1.3 Developing

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.
Make sure that the current imbalance
Note
between the phases do not exceed 5
% under normal operating conditions.
Determine if the supply power service is a two-
transformer 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.