Before starting work on the pump, make sure that the electricity
supply has been switched off and that it cannot be accidentally
switched on.
Correct earthing for all borehole pump installations is essential for
safety and pump motor protection. Consult a licensed electrician for
advice on requirements.
The electrical connection should be carried out by an authorised
electrician in accordance with local regulations.
i) General Information
WARNING
WARNING
WARNING
4
4. ELECTRICAL CONNECTIONS
Ÿ
The rated maximum current, supply voltage and cosØ are given on a loose data
plate supplied with the pumps which must be fitted close to the installation site.
Ÿ
The required voltage quality for DAYLIFF DS motors measured at the motor
terminals is -10%/+10% of the nominal rated voltage during continuous
operation including variations in the supply voltage and cable losses.
Ÿ
All motors must be fitted with a mains isolator and coarse current protection in
the form of an MCB or fuse. Coarse current rating should be approx 3X
maximum rated motor current.
Ÿ
For all three phase motors and single phase motors above 1.1kW a DOL starter
is required. Note that starting current is between 4X and 6X the rated motor
current which due to the low inertia of a submersible pump is reached in about
0.1 seconds. DOL starting is therefore recommended for motor starting up to
30kW motor sizes as the total system load is less than with a Star Delta
alternative. For alternative starting arrangements options of a soft starter or auto
transformer starter should be used.
Ÿ
It is essential to provide motor protection from high/low current conditions
outside the limits of +10%, -10% of the rated full load running current, high
current protection being provided by a DOL starter overload relay. Also
recommended for 3-phase motors is protection against phase loss, phase
asymmetry and high/low voltage variations (<+10%, >-10%) of nominal
supply voltage which can be provided by a multi-function relay.
Ÿ
Also generally recommended unless water availability is assured is low level
protection to prevent the pump running dry.
