ABB Group * | Slide *
ABB High Voltage Products* | Slide *Design Motor Drive
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ABB Group * | Slide *
***Theory: Description of the basic function and different
configurations of operating mechanisms
Drive types: Description of the drive types we have, where are
they used
Summary****The circuit breakers contact system must be opened
and closed with an accurate and consistent speed. The operating
mechanism or circuit breaker drive, provides the energy for these
operations.At a tripping operation a latch shall open and release
the stored energy in the tripping spring so that the contacts can
open and interrupt the current. The tripping spring can be placed
internally in the operating mechanism or externally at the force
transmission system.At a closing command the Closing springs,
placed in the drive, shall both close the contacts and at the same
time charge the tripping spring. This is a safety feature that
ensures that a closed circuit breaker always has a charged tripping
spring and are ready to interrupt a fault current.*Operating
mechanisms are used to provide the energy required to move the
contact system of an SF6 gas interrupter. Regardless of the type of
interrupter or operating mechanism design chosen, all operating
mechanisms must perform five (5) basic functions.
First, an operating mechanism shall provide a means to Charge an
energy source to be used during an open or close operation. Once
charged, the energy source shall be capable of Storing the energy
until it is called upon to operate the circuit breaker. The Release
of stored energy shall be highly reliable and consistent while the
Transmission of the stored energy to the interrupter contacts shall
be as simple and efficient as possible. Finally, an operating
mechanism shall provide a Control and Signaling interface to a
networks control and protection system.
While there are many existing designs of operating mechanisms,
they differ primarily in the way in which they meet requirements
for Energy Storage, Energy Charging, Energy Release and Energy
Transmission.**Live tank circuit breakers are typically equipped
with three (3) phases per circuit breaker as shown. In some cases,
however, a circuit breaker may include only one phase (e.g.
application in the neutral connection of a reactor) or two (2)
phases (e.g. railway applications). Taking the standard three-phase
circuit breaker as an example, circuit breakers may be either
three-pole or one-pole operated.
In three-pole operation, the three-phases of the circuit breaker
have a common operation. That is, if one is open, closed or moving
(i.e. opening or closing), the remaining poles must be in the same
position or performing the same operation. Three-pole operation
requires that there is a mechanical linkage connecting the three
phases. The energy required to operate the three-poles is stored in
one common operating mechanism.
Single-pole, operation simply means that the position or
operation of one or more poles is independent of the remaining
poles. Therefore, it is possible to have one or more poles in the
open position while the remaining poles are in the closed position.
Single-pole operation requires that each pole have its own
operating mechanism. The only link between the poles is then an
electrical link via the operating mechanisms. Note that, with
circuit breakers designed for single-pole operation, three-pole
operation is also possible (e.g. one common electrical signal which
will operate all three poles). *For single pole operation
configuration of circuit breakers, the common praxis is to use a
central control cubicle CCC as an interface between the circuit
breaker phases and the control system of the substation.The CCC
incorporates the common local control switches and interlocking
functions for the circuit breaker. The cubicle also contain
terminal blocks to which the electrical wiring or the three phases
are connected. These terminal blocks is the common electrical
interface for connection of the cabling to the control system.As an
option to the freestanding CCC ABB offers the integrated control
cubicle, ICC, concept. Here the freestanding cubicle is replaced by
a slightly larger drive cubicle at the middle phase. This cubicle
facilitates the same functionality as the separate CCC.The ICC
configuration provides some benefits: Less material Less boxes at
shipment Larger extent of tests made in the factory, (for the
cabling) Prefabricated interphase-cabling with connectors at both
ends Less energy consumption, (no separate cubicle with additional
heaters needed)****ABB is the most experienced spring-drive
supplier, and spring drives have been used since 1940.
The operating mechanism has five basic functions:Energy storage,
in the springs (capacitor bank for motor drive)Release the energy
at specific moment. Time consistency over the time is also a
important factor for controlled switching.Energy transmission, from
the operating mechanism to the interrupter. The transmission shall
be as simple and efficient as possible.Energy charging, in other
words, tense the springsProvide control and signaling, in other
words it is the interface to the networks control and protection
system. The mechanical chain of a circuit breaker also incorporate
a tripping spring that delivers the energy for opening of the
contacts. The tripping spring is charged by the operating
mechanism. ABB deliver well proven and reliable spring operating
mechanisms. Totally we have delivered over 150 000 spring drive
operating mechanism worldwide. FSA is design for low energy
requirements.BLK is designed for medium energy requirements.BLG is
designed for the highest energy requirements. Non of our
competitors can match that performance with a spring-drive
operating mechanism. As an alternative for applications that
require daily operations ABB can also provide the digital
controlled Motor Drive. For example, capacitor- or reactor bank
switching can require up to 700 operations/ year and Motor drive is
a ideal solution for these cases. The benefit for the customers
with our spring-drive operations is that our optimized well proven
simple design will minimize the total maintenance cost during the
lifetime. **The table shows the possible combinations of spring
drives and circuit breaker types*The FSA is a drive developed for
the less energy demanding circuit breakers. The drive was
originally designed for the ED circuit breakers, but has been
improved and reinforced to be able to handle both single and three
pole operation of the LTB-D, (72-170 kV) circuit breakers as
well.The drive contains both the tripping spring and the closing
spring in the same enclosure.
Technical details:Both springs in the same cubicleCam disc
principleIdentical close & trip latches*BLK have a well proven
design and have been produced in large quantities. More than 28,000
BLK operating mechanisms delivered since the production start. The
dive is compact due to the use of clock springs. Very easy to
maintain. Same type of triple action latches both for opening and
closing ensures extremely stable operating times independent of
ambient temperature.
Technical details:Excenter principleClock springIdentical close
& trip latches*With over 50,000 BLG mechanisms delivered, ABB
is confident that the design is one of the most reliable on the
market.The BLG contains a closing spring package that can be
equipped with either two or four springs dependent of the
application. The drive is very strong and are used to operate
circuit breakers up to 800 kV.Also here the stability of the
operating characteristics is ensured by the triple action latch
system.A rotating cam disc is used to charge the tripping spring at
closing operations
Technical details:Cam disc principleModular design with 2 or 4
springsChain system for spring chargingIdentical close & trip
latches
*The motor drive represents a technological step in operating
mechanism development. The motor drive system has a simplified
mechanical system to limit needed maintenance and increase
reliability.The only moving part of the operating mechanism is the
rotor of the motor. The mechanical system between the motor and the
breaker poles are also made as simple as possible. The result is a
drive that do not need any maintenance since it has no wearing
parts. During development test the drive has been exposed to more
than 40,000 operations without any failures.The elimination of
drive maintenance makes a circuit breaker equipped with motor drive
ideal for applications with high amounts of operation, such as
capacitor bank or reactor bank applications.The Motor drive was
launched in 2004 and has since then been installed in several
hundreds of installations all over the globe.
Technical details:Electrically stored energyServo motor
operatedSelf supervisionLow sound level
*Superior time consistencyTriple action latches allow an
extremely high force to be supported while requiring relatively low
force for actuation. Because the triple action latch can support
such high loads (e.g. 40 kN in the BLG design), it is very stable
and maintains its latched position until called upon to operate.
The triple action latch design also gives very consistent operating
times, even when subjected to variations in control voltage and
ambient temperature. While competitors have recently designed
spring operating mechanisms, none use a triple action latch. Single
or double action latches used in competitor designs do not provide
the same consistency in operation time as the ABB latch. Thus,
while ABB operating mechanisms are ideally suited for controlled
switching applications, our competitors designs are not as
suitable. Moreover, ABBs triple latch design have a low actuating
force and therefore the uses 200 W trip coil compared to our
competitors that uses 400 W coils. A smaller energy need is a
benefit specially if the substation require backup power i.e.
batteries. Switchsync applications needs good accuracy of the
opening and closing times to work properly and give the results
that the synchronization Is intended to give. The well designed ABB
latches provides this accuracy and consistency in the operating
times and makes the ABB circuit breakers suitable for controlled
switching applications.*Find more detailed information regarding
operating mechanisms in the Live Tank Circuit Breaker Buyers and
Application guides.*Benefits of spring ABB drivesTime consistent
operations due to the well designed triple action latches, that
makes the circuit breakers suitable for controlled switching.High
reliability and availability is reached with extensive testing
during development. All new designs are tested with mechanical
endurance tests beyond the IEC requirements of 10,000 operations to
find the weak spots and then improve them.Low maintenance costs
since the service intervals are long. 15 years in service or 5,000
operations until first outage for maintenance.A spring drive is
extremely consistent independent of ambient temperatures, the
drives does not contain any oil that can leak or change viscosity
in the kinematic system.According to studies performed by Cigr a
spring operating mechanism provides the most reliable operation of
circuit breakers.****** ****
