18-01-2013, 02:53 PM
N-Series automatic circuit recloser
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Introduction and Features
The Nu-Lec Industries N-Series gas
insulated automatic circuit recloser (also
known as a circuit breaker) provides the
features of traditional reclosers, plus the
benefits of up to date design optimised for
automation, remote control and monitoring,
now or in the future.
The development of this product was
driven by customer demand for improved
return on capital investment in the
distribution network. After carefully
evaluating customers’ needs, the N-Series
gas insulated reclosers were developed to
achieve optimum performance and
reliability, making use of the latest in
available technology in vacuum arc
interruption and microelectronics. The
result is a competitive world-class product
of which we are justly proud.
In the past, distribution equipment such as
reclosers have been purchased only to
support load growth. Today, your
customers, the electricity consumers, are
demanding reduced outages and lower
tariffs. We at Nu-Lec Industries are
continually working to provide advanced
equipment needed for tomorrow’s
competitive electricity distribution system.
By using this technologically advanced
equipment, operating costs will be
reduced, revenue will be increased through
reduced outages and capital works can be
deferred through better management of
existing plant.
In addition to automatic circuit reclosers,
the Nu-Lec Industries family of switchgear
includes a range of remotely controlled and
monitored pole mounted load break
switches and sectionalisers as well as
remote control and monitoring software.
This product family is a complete solution
for distribution system automation.
Reduced Purchase Cost
• Remote Terminal Unit (RTU) and modem are included in the standard
equipment. No additional RTU, modem, power supplies, batteries, wiring,
connectors or enclosures are required.
• A 400A insulated cable connection kit is provided as part of the standard
package. However, 250A, 630A and 800A cable kits are also available, as
well as a bare terminal kit for applications up to 15kV.
Reduced Installation Costs
• Lightning arrester mounting, up to 630A insulated cable tail kit and pole
mounting brackets are provided in the standard package. An optional Voltage
Transformer (VT) for auxiliary supply is available.
• Configuration of the unit is from the Operator Control Panel, making
commissioning simple.
• These automatic circuit reclosers are ideally suited as low cost feeder circuit
breakers in outdoor zone substations. In this application, connection into the
substation control or automation system is simple and low cost.
Reduced Operating Costs
• The integral protection relay provides fast isolation of faults, reducing
damage.
• The recloser constantly monitors line current and voltage without the need for
additional statistical measurement devices. This data can then be used for
forward planning and optimisation of existing plant. This will reduce
distribution system losses.
• Long lifetime, low maintenance equipment reduces lifetime cost.
DSA/SCADA Compatibility
When used with a compatible Distribution System Automation (DSA) or SCADA
system, Nu-Lec Industries automatic circuit reclosers support remote control and
monitoring to provide the following advantages:
• Information on recloser status and fault current values transmitted to system
control allows fast location of the faulted line section, reducing the travelling
time of line crews.
• This same information allows informed remote switching which reduces the
affected area and quickly restores supply.
• Reclosers can be configured and settings managed from system control,
without technicians having to visit each individual recloser in the field, with a consequent reduction in staffing and improved system integrity.
Increased Revenue
• Supply can be quickly restored to unaffected areas, resulting in less outage
time and therefore increased revenue.
Deferred Capital Works
• Remotely controlled and monitored automatic circuit reclosers give an
improved knowledge of a system and provide better system control. Feeder
and substation load can then be remotely managed improving utilisation of existing plant. Purchase of new plant can then most likely be deferred for aconsiderable period of time.
Introduction and Features
N-Series Nu-Lec Industries
The N-Series gas insulated automatic circuit recloser is designed
around vacuum interrupters contained in a fully welded and sealed
316 grade stainless steel enclosure. The enclosure is filled with
sulphur hexaflouride (SF6) gas, which has excellent electrical
insulating properties, resulting in a compact and low maintenance
device.A pole mounted control and communications cubicle houses the Operator Control
Panel and microelectronics. This cubicle houses an electronic controller thatmonitors the circuit breaker and provides protection functions. A detachable control
cable is used to connect the cubicle to the circuit breaker. Combined together, thecircuit breaker and communications cubicle form a remotely controlled andmonitored automatic circuit recloser.
The circuit breaker is operated by sending a controlled pulse of current from astorage capacitor in the communications cubicle through a solenoid. This attractsthe mechanism plate which in turn closes the contacts in the vacuum interrupter.The contacts are held in the closed position by latch tongues resting on the trip bar.Opening of the contacts is achieved by releasing a controlled pulse of current froma capacitor through the trip coil. This attracts the trip bar armature, turning the tripbar and releasing the latch. The opening spring and the contact pressure springsaccelerate the contacts open. A flexible connection is provided to allow movement
of the contacts to occur.
Epoxy bushings insulate the main circuit conductors from the outer case andprovide a double “O” ring seal. They also provide the necessary insulation andsupport for the embedded voltage sensing screens and for the current
transformers. The bushings are DIN 47 636 (threaded option) and allow theconnection of alternative cable connection elbows if desired. Lightning arrestermounting is provided for installation convenience.
A standard kit for field fitting is supplied with the circuit breaker. It contains
polymeric bushing boots and 3 metre lengths of 185 mm² aluminium insulated
water tight cable tails rated at 400A. This arrangement results in an automatic
circuit recloser suitable for connection into an insulated conductor system, or a bare
conductor system, as appropriate. The fully insulated system provides freedom
from faults caused by birds and other wildlife.
An auxiliary voltage supply of 110, 220, 240, or 415 volts AC is required to power
the unit. Where this is inconvenient, a voltage transformer can be provided as a
purchase option. The control cubicle is connected by a control cable to the bottom
of the circuit breaker through a rubber covered plug/socket arrangement.
A clearly visible external pointer shows the contact position. The automatic circuit
recloser can be tripped from the ground by a hookstick. It can then be locked out
by opening the isolating switches located on the Operator Control Panel. These
switches are physically connected in series with both the Trip and Close solenoids.
The Pole Top Control Cubicle (PTCC) interfaces to the recloser via the control
cable and connects to the Switch Control Entry Module (SCEM) in the base of the
tank. The SCEM uses EEPROM memory to store all relevant calibration data,
ratings and number of operations conducted. The SCEM also provides the first
stage of electrical isolation and shorting electronics to short the CTs and CVTs in
the event the control cable is disconnected while current is flowing through the
automatic circuit recloser.
Circuit Breaker Overview
and Operation
Nu-Lec Industries
1. Insulated cable tails
2. Polymeric bushing boot
3. DIN 47 636 bushings
4. Current transformer
5. Lightning arresters
(optional) and
mountings
6. Vacuum interrupter
7. Contacts
8. Stainless steel tank
9. Contact pushrod
10. Contact pressure spring
11. Latch
12. Trip bar armature
13. Trip bar
14. Trip Coil
15. Cable to control cubicle
16. Cable entry cover
17. Switch Cable Entry
Module (SCEM)
18. Mechanism plate
19. Opening spring
20. Closing solenoid
21. Flexible connection
22. Gas filled tank
Legend
Cross Section of Circuit Breaker
N-Series gas insulated circuit breaker
N-Series
The advanced protection, data logging and communications
abilities of the N-Series recloser are made possible by the
technology housed in the control and communications cubicle. It
has been designed especially for outdoor, pole mounted operation
and is normally mounted low on the pole for ease of access by
maintenance personnel.
The cubicle is insulated and designed to minimise any temperature rise resulting
from solar heating. An internal equipment panel is used to mount all the equipment,
including the batteries, storage capacitors, mains transformer, low voltage circuit
breakers, Control And Protection Module (CAPM), Operator Control Panel and
radio or modem. These components are carefully located so that the heat
generating parts are at the top, while the battery is at the bottom to keep it cool. In
this way battery life in excess of 5 years can be achieved.
All weather access is provided to the Operator Control Panel through a lockable
door on the front of the control cubicle. Vents are screened against vermin entry
and the door is sealed against the outer with a rubber extrusion. All electronic parts
are well protected from entry of moisture and condensation ensuring a long lifetime.
Three models of control and communications cubicle are available, Tropical,
Moderate and Temperate. The Tropical version is well ventilated and is suitable for
climates where the ambient temperature can reach 50°C and only occasionally
goes below 0°C, with a lower limit of -10°C.
The Moderate version has reduced ventilation and is used where temperatures
rarely go above 40°C and occasionally go below -5°C, with a lower limit of -15°C.
The Temperate model has a heater installed, making it suitable for climates where
the temperature rarely goes above 40°C but can fall as low as -30°C.
All three cubicles are fitted with the same electronics and incorporate the functions
of an overcurrent protection relay, a sensitive earth fault relay, a reclose relay, and
a remote terminal unit. Additionally, the electronics measure line current, voltage,
real and reactive power, fault currents, and stores these for transmission or off-line
analysis.
A unique feature of the Nu-Lec Industries automatic circuit recloser is the built in
microprocessor controlled power supply. This provides uninterrupted operation of
not only the recloser and protection relay, but also the communications radio or
modem. No other power supplies are required for connection into your SCADA or
Distribution Automation System.
Due to careful design the efficiency of all parts is extremely high, allowing a battery
hold up time of five days after auxiliary supply failure (from fully charged battery,
excluding telemetry radio or modem usage). The architecture used has the
advantage that the circuit breaker operation is independent of the high voltage
supply, relying on a set of batteries charged by the auxiliary supply.
Due to sophisticated power supply management techniques, a circuit breaker
operation is always guaranteed when attempted and alarms are raised over the
telemetry when auxiliary power is lost.
A communications radio or special modem can be mounted within the control and
communications cubicle. A V23 FSK modem is included as standard equipment.
Communications Cubicle
Overview
Pole Top Control & Communications Cubicle
Control and Protection Module (CAPM) Circuit Board
N-Series Nu-Lec Industries
Nu-Lec Industries’ automatic circuit reclosers provide many
outstanding advantages to the user. New and innovative features
have been made possible by the intimate way the pole mounted
circuit breaker and communications cubicle work together. The
block diagram below shows how the two items are interfaced. The
heart of the unit is the Control and Protection Module (CAPM) and
the intelligent Operator Control Panel.
HV Line signals are connected into the electronics module by direct connection to
the analogue front end. Special extended range current transformers provide a
range from 1A to 16,000A for measurement and protection. Embedded voltage
screens accurately image the primary voltage value and phase relationship,
allowing measurement of voltage, current, power factor and frequency in the
electronic module.
Each recloser is provided with an Operator Control Panel which has a four line
liquid crystal display with back lighting for night operation. From here a user can
access and program the many measurement and protection features available.
Three levels of user interface with the Operator Control Panel are provided as
follows:
1. Operator Level
This allows basic operation like Trip, Close and display of settings, such as:
• Protection settings and fault history
• Line measurements and historical data
• Recloser functions such as:
Remote control ON
Local control ON
Sensitive Earth Fault ON/OFF
Earth Fault ON/OFF
Auto reclose mode ON/OFF
Close/Trip ISOLATE
• Alarms/Status such as:
Auxiliary supply fail
Battery supply fail
Lockout
Gas loss
2. Technician Level
This level is password protected at the user’s discretion in the “Engineer Level” and
allows the setting of all protection related parameters.
3. Engineer Level
This is accessible through a laptop or desktop computer and allows advanced
customisation of the operator panel, setting of passwords, and all the Operator and
Technician Level functions.
Telemetry Interface
The Nu-Lec Industries automatic circuit recloser can be interfaced to your SCADA
system either through its built-in V23 modem and a radio, or its RS232 port and a
modem of your choice. A variable voltage uninterruptible power supply is included
for the radio or modem, which can be mounted inside the communications cubicle.
Almost all telemetry protocols can be supported. DNP3 and IEC870 are two of the
available protocols.