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Installation of a Form 5 control on a 3-wire uni-ground sys-
tem must include the following:
• Protection of the recloser bushings and the supplying
transformer with lightning arresters.
• Grounding of the recloser head and tank.
• Grounding of the transformer tank.
• Grounding of the control cabinet.
• Grounding of the SCADA equipment.
S280-79-10
37
!
SAFETY
FOR LIFE
Surge
Arrester
Recloser
Head Ground
Surge
Arrester
Surge
Arrester
Arrester Ground
Recloser
Supply
Voltage
Pole
Ground
Form 5 LS
Control
Customer Ground
Connection
at External Lug
GND
NEU
HOT
Input Terminal Block
Control
Cable
AC
Neutral
Form 5 LS Control
Input Terminal Block
Supply Voltage
Transformer
ELECTRICAL CONNECTIONS - Dedicated Supply
Transformer
Line
to
Line
Voltage
External Ground Lug
NEU
AC
Control Height must be
3 Meters (10 feet)
minimum above earth
Figure 31.
Recommended grounding method for the Form 5
Control installed on a 3-wire uni-grounded system.
IMPORTANT: All external inputs to the Form 5 con-
trol must be routed within 8 inches of their correspond-
ing ground. During a surge, a potential of
approximately 1.5kV per foot can develop in the con-
ductors. Differences between conductor and ground
path lengths can add additional stress to the control
components in the event of a power surge.
IMPORTANT: In pole-mounted applications, a
ground connection must be made between the
recloser, transformer, recloser control, and SCADA
equipment for proper protection of the equipment. The
pole ground must be sized per local utility practices to
minimize the impedance between the recloser and the
control.
WARNING: Hazardous Voltage. Use locally
approved operator safety procedures for proper
insulation when maintaining this equipment. High Volt-
age step and touch potential is characteristic in uni-
ground systems. Failure to comply can cause death or
severe personal injury. T262.0
!
CAUTION: Exported Potential. Do not make
direct electrical connections to remote devices. All
SCADA equipment must be mounted locally or con-
nected using the fiber-optic or radio communication
accessory. Direct connections to remote devices can
produce exported potential causing equipment damage
or personal injury. T263.0
!
CAUTION: Hazardous Voltage. Do not use a
shared low voltage network to power the recloser
control unless the network is specifically designed to
withstand maximum ground potential rise. Ground
faults on a high voltage network can create a rise in
ground potential. T264.0
!
Grounding on a 3-Wire Uni-Grounded System