Grundfos SP Installation And Operating Instructions Manual page 19

6.7.4 High-voltage surge arresters
Use a high-voltage surge arrester to protect the
motor against lightning and switching surges.
Lightning voltage surges in power lines are
caused when lightning strikes somewhere in the
area.
Switching surges are caused by the opening and
closing of switches on the main high-voltage
distribution power lines.
Install the correct voltage-rated surge arrester
on the supply side of the control box. See fig.
and fig. 15. The arrester must be grounded in
accordance with the National Electrical Code
and local codes and regulations.
Single-phase
power supply
Lightning
arrester
Fig. 14 Single-phase installation
Three-phase power supply
Ground
Lightning
arrester
T1 T2
To MS motor
Fig. 15 Three-phase installation
14
Ground
True
grounding
point
Pump
control
panel
Install
lightning
protectors
before fuses
or circuit
breaker
T3
True
grounding
point
The warranty on all three-phase
submersible motors becomes void in
these cases:
• The motor is operated with single-
phase power through a phase
converter.
• Three-leg ambient compensated,
Note
extra quick-trip overload
protectors are not used.
• Three-phase current imbalance is
not checked and recorded. See
section 7.
• High-voltage surge arresters are
not installed.
6.7.5 Control box or panel grounding
WARNING
The control box or control panel must
be permanently grounded in
accordance with the National
Electrical Code and local codes or
regulations.
The ground wire must be a bare copper
conductor at least the same size as the
submersible drop cable wire size.
Run the ground wire as short a distance as
possible and fasten it securely to a true
grounding point.
Startup.
19