8
NOVA™ STS Single-Tank, Triple-Single, Electronically Controlled Recloser
INSTALLATION AND OPERATION INSTRUCTIONS
MN280046EN May 2016
Grounding with a remote supply voltage
transformere: 4-wire multi-grounded, 3-wire
ungrounded, or impedance-grounded
Installation with a remote supply voltage transformer must
include the following (refer to Figure 9):
●
●
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.
Ground Tie
Pole
Surge
Arrester
Supply Voltage
(12 gauge minimum)
Arrester
Ground
Surge
Arrester
Form 6
Control
Pole
AC
NEU
GRD
NEU AC
Input Terminal
Block
Control Cable(s)
Arrester
Ground
Customer Ground Connection
at external lug
Surge
Arrester
NOVA STS
Recloser
Recloser
Ground
Connector
Transformer
Pole Ground
(6 gauge minimum)
NOTE: Distance between
transformer and recloser
should be one pole span
or less.
Figure 9 . Recommended grounding method for NOVA
STS recloser with Form 6-TS microprocessor-based
recloser control .
Recloser operation
WARNING
This equipment is not intended to protect human
life . Follow all locally approved procedures and safety
practices when installing or operating this equipment .
Failure to comply can result in death, severe personal
injury, and equipment damage .
G102 .1
WARNING
Hazardous voltage . Do not rely on the open position
of the yellow operating handle or the contact position
indicator; it does not ensure that the line has been
de-energized . Always establish a visible disconnect .
Failure to follow proper safety practices can result in
contact with high voltage, which will cause death or
severe personal injury .
G114 .1
A current transformer senses line current from each phase
of the NOVA STS recloser and inputs this information to the
Form 6 Triple-Single microprocessor-based recloser control.
The recloser responds to trip and close commands from
the control per the settings programmed in the control.
Refer to
Service Information S280-70-7 Form 6 Triple-
Single, Microprocessor-Based Pole Mount Recloser Control
Installation and Operation Instructions
for control operation
information.
Vacuum interrupter
Arc interruption takes place within the sealed vacuum
interrupter. Eaton’s Cooper Power series vacuum
interrupters employ axial-magnetic field contacts. Slots are
machined into the contact support structure producing a
magnetic field along the axis of the interrupter. This axial-
magnetic field keeps the arc in an easier-to-interrupt diffuse
mode, resulting in less power in the arc that needs to be
dissipated, resulting in extended operating duty.
Mechanism tripping and closing
The NOVA STS recloser is comprised of three single-
phase NOVA reclosers. Each recloser utilizes a magnetic
actuator for fast, efficient latching. A rare-earth neodymium
magnet provides latching forces in excess of 240 pounds,
eliminating the need for mechanical latches.
While in the closed position, the magnetic field established
by the magnet is coupled with the iron assembly to provide
a latching force for the movable plunger. The magnetic
force is concentrated at the plunger-assembly interface and
provides the latching force required to keep the mechanism
closed. The assembly also houses the trip and close coils
that provide the energy to operate the mechanism.
To open the main contacts, the trip coil is pulsed with
electrical current, which cancels the magnetic field. A
compression spring in the center of the coil moves the
plunger assembly to the open position. As the plunger
moves, the magnetic field strength decreases as the air gap
increases, due to the difference in the relative permeability
of free space and the ferrous plunger. Once in the open
position, the compression spring keeps the unit open.
A trip and close capacitor stores the necessary energy for
operating the recloser. As a result, trip energy is available
following any close operation. This capacitor is charged by
the control nominal 24 V battery and/or power supply.
