Mechanism
from Cooper Power Systems
THE ULTIMATE GAS-FREE, OIL-FREE AND
MAINTENANCE-FREE SOLUTION FOR
AUTOMATION, PROTECTION AND SWITCHING
APPLICATIONS
NOVA Technology
Kyle Distribution Switchgear
Mechanism
NOVA Mechanism
Dependable Magnetic Latching
NOVA’s simple operating mechanism is designed with
utilities’ maintenance-free philosophy and desire for
lightweight dielectric material. It is small and lightweight, reducing installation time and resources.
Customer Benefits
136 kilograms (300 pounds) of magnetic force ensures
complete, undeniable latching. Latching travel is less
than one inch, providing efficient response to ensure
rapid fault clearing and reclosing time. Because latching is achieved with magnetic force, there are no closing or opening springs to stretch or break.
• Fewer mechanical parts mean no maintenance.
10,000 Operations
• Tested for a minimum of 10,000 operations to ensure
long, dependable life.
The mechanism has been tested for a minimum of
10,000 operations with minimal component wear and
no lubrication needed.
• 136 kilograms (300 pounds) of magnetic latching
force eliminates maintenance on triggers and alignment.
Low-Energy Power Requirement
• Low-energy power requirement provides deadline
and bi-directional switching.
The mechanism can be powered from a control battery,
which is contained in all Kyle recloser controls. The
pulse energy from the battery, used to charge the mechanism capacitors, is only 64 watts.
• Reduced training costs via compatibility with Kyle’s
complete family of controls.
Deadline and Bi-directional Switching
The mechanism uses a proven magnetic latching design
which provides accurate, reliable opening and closing
operations. Two low-voltage heaters prevent condensation and corrosion. Components are available in plated
steel and aluminum, or stainless steel.
Deadline switching is available from any Cooper
Power Systems control equipped with dc-operated
recloser mechanisms. Several hundred deadline switching operations are available without ac power.
Distribution automation costs are reduced while providing greater operational flexibility and reliability.
• Visible indication of OPEN/CLOSE for safety.
Heater
Magnetic Actuator
3-Phase Mechanism
Manual Open Handle
CT Protection Board
OPEN/CLOSE
Position Indicator
View of operating mechanism with bottom cover removed.
2
Actuator Board
Trip & Close Capacitors
Mechanism
Theory of Operation
At the heart of the assembly are two rare earth
neodymium magnets. The high energy magnets provide latching forces in excess of 136 kilograms (300
pounds), eliminating the need for closing/opening
springs and mechanical latches.
A simple design assures reliable operation of the
NOVA mechanism by use of a magnetic actuator.
Magnetic force provides faster, more efficient latching
action than mechanical force. Magnetic latching utilizes
fewer moving parts, which results in less wear on
mechanism components.
Neodymium magnets
Closing Coil
While at rest in the closed position, the magnetic fields
established by the two magnets are coupled in the iron
yoke assembly to provide latching forces for the movable plunger. The magnetic forces are concentrated at
the yoke-plunger interface and provide the latching
force required to keep the mechanism closed. The yoke
also houses the trip and closing coils that provide the
energy to operate the mechanism.
Trip Coil
To open the main contacts, the trip solenoid is pulsed
with electrical current which produces an electrical
field. The electrical field, concentrated in the center of
the coil, moves the plunger assembly toward the open
position. As the plunger moves, the magnetic field
strength-density increases as the air gap decreases, due
to the difference in the relative permeability of free
space and the ferrous yoke. The magnetic fields are reestablished in the open position to latch the unit open.
Iron Yoke Assembly
Magnetic actuator located inside the mechanism housing.
Magnetic Actuator Operation
Trip (Open) Position
Closed Position
S
N
S
N
S
N
N
S
N
S
N
S
I
I
Operation of the Nova magnetic actuator.
3
Mechanism
Operation of Mechanism Linkage
Manual Operation
The mechanism linkage utilizes a short travel distance
of approximately 19mm (0.75 inches). This short travel
distance gives the NOVA recloser a fast, consistent
response time. It also reduces mechanical wear, due to
the minimal amount of travel required to open and
close the device.
Manual opening is accomplished using the manual
operating handle. When the mechanism is electrically
closed, the manual opening spring is charged. Once
charged, the spring can overcome the 406.5 Nm (300
foot-pound) latching force of the neodymium magnets
that holds the contacts in the closed position.
The magnetic actuator is an electromechanical device
capable of extremely fast response times. This attribute
is particularly advantageous for minimizing clearing
and response time in providing instantaneous reclose.
The mechanism used in the NOVA does not use opening or closing springs for electrical operation. When
electrically operating the NOVA mechanism, the recloser makes use of a bi-stable linear actuator that uses two
neodymium magnets, two opposing coils and a
plunger.
Some competitive units use a single coil design in the
magnetic actuator. This coil must induce a magnetic
field which cancels the permanent magnet’s field during closing or opening operations. Since the direction
of the magnetic field must be reversed for tripping versus closing operations, and since only one coil is used,
the field across the magnet must be reversed. Years
ago, during Kyle’s evaluation of potential technologies,
this scheme was judged highly undesirable due to the
potential of demagnetization of the permanent magnet.
OPEN/CLOSE
position indicator
Manual
operating handle
NOVA recloser manual operating handle.
OPEN/CLOSE Position Indicator
Open and close operations of the NOVA mechanism
can be viewed using the indicators in the recloser controls and verified with the Open/Close indicator on the
switchgear.
The contacts OPEN/CLOSE indicator is visible from
side and bottom of unit resulting in a field of vision
spanning roughly 150º.
4
Mechanism
Operational Flexibility
• Compatible with existing controls
Ultimate operational flexibility is provided by offering
the customer a choice of an ac or dc version of the
NOVA recloser product. Each version incorporates the
same magnetic actuator and is essentially mechanically
equivalent, but differs in electrical operation. Both
ensure reliable operation throughout all operating conditions.
• Standardization of components such as controls and
cables
• Familiar theory of operation
NOVA ac Operation
Consistent with other Kyle reclosers, both 120Vac and
240Vac closing power options are available for the
NOVA ac recloser. The ac voltage is then rectified to
48Vdc to charge the trip and close capacitors and provide the electrical pulses for the two operating coils on
the magnetic actuator. A trip operation does not require
the presence of ac voltage and recloser closing is
accomplished from the source-side low-voltage input.
Application Considerations
Through 55 years of industry experience, customers
have become accustomed to the operation of the Kyle
product lines. This familiarity is the basis of the ac
operated NOVA. Today, control power is provided
from a customer-supplied potential transformer, located on the source-side of the mechanism. This historical
investment, and complete interchangeability with all
Kyle controls, is the basis of the ac-powered NOVA.
Trip and closing signals are provided via the electronic
control to the mechanism through the identical 14 conductor control cable used with all Kyle electronically
controlled reclosers. Retrofitting to an existing installation simply requires changeout of the switchgear.
Benefits Include:
• Reliable fault clearing
• Independent trip operation
• Live line closing
NOVA ac
120/240Vac
Energy Source
NOVA ac
Control
Cable
Potential
Transformer
(120/240Vac)
O
P
E
N
Electronic
Control
120Vac/240Vac
14 Pin Cable
Power Cable
NOVA ac cable connections.
5
Mechanism
NOVA dc
Benefits Include:
Customers with installations which require the capability for numerous deadline and bi-directional switching
operations can specify a newly developed NOVA dc. In
these cases, NOVA operation will come primarily from
a battery contained in the control cabinet, providing
several hundred operations. Power is supplied to
charge the control battery and provide voltage for the
mechanism heaters.
• Deadline and bi-directional switching
• Battery backed operation
• Single cable installation
• Compatible with existing controls with an upgrade kit
Increased use of automation or alternate feeder direction make this emerging option attractive based on
installation economics.
NOVA dc
19 Pin Cable
Control
Cable
NOVA dc
Potential
Transformer
(120/240Vac)
O
P
E
N
Electronic
Control
120Vac/240Vac
Power Cable
NOVA dc cable connections.
6
Mechanism
NOVA dc Operation
A new 19 conductor cable interfaces the NOVA dc to the
control through the interface circuit board. In addition
to control functions, the cable provides ac power to the
mechanism heater. Cable lengths up to 200 feet are permitted.
Trip and close operations are performed with the control battery and are independent of the ac power provided. Deadline operation is possible with the addition
of a dc-to-dc converter and interface circuit board to the
control. Retrofit kits are available which allow customers to modify existing controls for NOVA dc operation.
Upon loss of ac power, trip and close capacitors maintain their charge from the control battery.
NOVA Mechanism
The dc-to-dc converter board converts the control’s
24Vdc battery supply to 53Vdc to drive the trip/close
capacitors in the NOVA mechanism. The output of the
board is separately fused and monitored with a red
LED for operator indication. The board also houses
voltage monitoring and conditioning circuits which protect the control battery from failure and provide hundreds of trip/close operations without ac power.
The NOVA mechanism uses a proven magnetic latching design which provides accurate, reliable opening
and closing operations. Designed with a simple operating mechanism, NOVA is congruent with utilities’
maintenance-free philosophy and desire for lightweight
dielectric material. It is small and lightweight, thus
reducing installation time and resources.
The mechanism provides customers with expanded
distribution automation opportunities with the NOVA
ac and NOVA dc. This ensures greater service continuity in electrical system operation.
dc-to-dc converter
board
The magnetic actuator mechanism represents one of the
key building blocks which comprise our modular product called NOVA.
Recloser interface board
Kyle® FXB recloser control with dc-to-dc converter board.
7
Mechanism
©1997 Cooper Power Systems, Inc.
Kyle® is a registered trademark of Cooper Industries, Inc.
NOVA™ is a trademark of Cooper Industries, Inc.
Bulletin 97071 • December 1997 • New Issue
P.O. Box 1640
Waukesha, WI 53187 USA
www.cooperpower.com
KTM
12/97