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Latest News / Terasaki | TemPower | Air Circuit Breakers

Terasaki | TemPower | Air Circuit Breakers


Overload Protection
Earth Leakage Trip Function
  Adjustable from 40-100% of rated current. True r.m.s detection up to the 19th harmonic, a distant vision for the competition who rarely see past the 7th. Neutral protection for all those Triple-N harmonics, such as 3rd, 9th and 15th. Also in case we forgot to mention, a "thermal memory" is available on the AGR-21B/31B.     Used in conjunction with Zero phase Current Transformer (ZCT), this function provides protection against leakage to earth of very small levels of current. Trip Alarm indication, and contact is available to enhance the level of system protection
Reverse Power Trip Function   Phase Rotation Protection Function
  (S-characteristic) This feature provides additional protection when paralleling generators. The AGR-22B/31B OCR for generator protection with the reverse power trip function, negates the need for installation and wiring in an external reverse power relay. This feature is available using an AGR OCR with a generator "S" type characteristic only.     This function detects the negative-phase current occuring due to reverse phase or phase loss and prevents burnout of a motor or damage to equipment
Two Channel Pre-Trip Alarm Function (optional)   Advanced L.C.D Display, Over Current Relay
  This function can be used to monitor and switch on additional power backup to feedcritical circuits. For example, the function can be set so that when a pre-trip alarm is activated, an emergency generator starts to ensure a constant supply. This feature is only available on some AGR-22B/31B OCR models with a generator "S" characteristic     The AGR-31B OCR comes standard with the backlit LCD display. It can monitor and indicate phase currents, voltages, power, energy, power factor, frequency, and more. The backlit LCD is optional for AGR-21B and AGR22B.
N-phase Protection Function (optional)   Remote Communication Protocals (optional)
  In 3-phase, 4-wire systems that contain harmonic distortion, the 3rd harmonic may cause large currents to flow through the neutral conductor from sustaining damage or burnout due to these large currents. Available in all OCR's except for generator "S" characteristic types     Data communications via Modbus, an open network, are supported. Energy Management - I, V, kW, kVar, cosØ, frequency Intelligent Fault Analysis - Status, fault type, fault size, tripping time, fault history Maintenance Information - Trip circuit supervision, contact temperature monitoring.
Ground Fault Trip Function   Contact Temperature Monitoring Function (optional)
  This function eliminates external relays to provide a ground fault protection to TN-C or TN-S power distribution systems on the load side. Ground fault protection on the side is also available as an option.     This function monitors the temperature of the ACB's main contacts. An alarm indicates when the temperature exceeds 155°. Continuous monitoring of the contact temperature provides valuable input for preventative and predictive maintenance programs.
Internal Contruction
  • One of the smallest ACBs in the world.
  • Double contact breaking system. Fast clearing time of 30 msec.
  • Double insulated front body, field fit accessories.
  • Icu = Ics = Icw. 65kA, 85kA, 100kA and 120kA versions
  • Characteristic curve to IEC 60255-3. True generator protection curves in accordance with Marine Classification Rules.
  • Monitoring of contact temperature.
  • Reverse power protection. Zone Interlocking Unrestricted and/or restricted ground fault protection.
  • Double opening and closing coils.
  • All standard voltage options are available for protection relays.
  • Withdrawable plug-in version - main clusters fitted to ACB, not to fixed busbars.
  • Reducing switchboard size and cost.
  • Increase reliabilty and extendad life under fault conditions
  • Facilitates simple maintenance, upgrade and retro fitting.
  • High short circuit withstand provides full selectivity up to 100kA and means no reduction of performance when tripped by an external relay.
  • The most flexible relay on the market ensures selectivity and protection are always achieved.
  • Provides diagnostic information and reduces factory down time.
  • Integrated generator protection functions within the one relay.
  • Increased reliability for critical applications. Increased Redundantly.
  • No additional cost or configuration.
  • Clusters can be maintained without mains being switched off.
  • The TemBreak 2 enhanced electronic breaker with integrated VT and CT monitors the current, voltage, instantaneous electrical power, integrated electrical energy and power factor of a circuit.
  • Using Modbus protocol allows data such as measured values and events / fault logs to be transmitted to an external device (T2ED) / network
  • 250A Frame size models have measurement and data communications options but no LCD display.
  • 400A Frame size and above have LCD display which provides local indication.
  • Phase Currents, Line Voltages (and max values), Power Factor, Electrical Power and Electrical Energy.
  • Neutral - Phase / Phase rotation protection and Ground fault trip
  • 1st to 19th harmonic currents for each phase.
  • Long time delay and instantaneous trip, Short time delay trip,
  • Under fault conditions the cause of the fault and the fault current are indicated on the LCD.
  • Data in memory is stored even if the power is lost. These events and fault logs can be viewed after power is restored.
  • LCD orientation corresponds to breaker orientation, when ordering specify HL = Horizontal (move handle left for On) HR = Horizontal (move handle right for ON), V = Vertical (move handle up for ON)
  • On fault status the cause and fault currents are indicated on the LCD display and stored in non-volatile memory (can be viewed when power is restored)
  • More detailed data monitor / display options are avaialble please refer to the TemBreak2 catalogue
  • 800A frame size current ratings:- 250A - 630A, 320A - 800A
Current Rating By Frame Size
  • 250A frame size current ratings:- 16A - 40A, 50A - 125A, 63A - 160A, 100A - 250A,
  • 400A frame size current ratings:- 100A - 250A, 160A - 400A,
  • 630A frame size current ratings:- 250A - 630A
  • 800A frame size current ratings:- 250A - 630A, 320A - 800A
  • 1000A frame size current ratings:- 250A - 630A, 320A - 800A, 400A - 1000A
External display for TemBreak 2 ACB and MCCB's. It displays circuit measurements and information about the installed breaker. T2ED is also able to transfer all this information directly to a Modbus network
Modbus connection is direct from the circuit breaker or the T2ED, no need for communication modules.
Displayed Reading
  • Line Voltage
  • Phase Voltage
  • Power (effective/apparent/reactive)
  • Demanded Power (effective/apparent/reactive)
  • Maximum Demanded Power (effective)
  • Energy (effective/apparent/reactive)
  • Frequency
  • Power Factor
  • Maximum Phase Current
  • First Phase Current
  • Second Phase Current
  • Third Phase Current
  • Neutral Current
  • Ground Fault Current
  • Negative Phase Current
  • Maximum Phase Voltage
  • Circuit Breaker Protection Settings
  • Trips Event Log
  • Alarms Event Log
  • Harmonic Current (up to 19th harmonic)

Often ageing switchgear may require an upgrade and maintenance to meet modern operational and safety requirements. To replace old equipment can be extremely expensive, retrofitting of circuit breakers can offer a huge saving rather than replacing all the equipment.

ACDC Dynamics provides retrofitting and maintenance services that maintain the existing copper work and steelwork, while replacing the prime functional components. We provide complete retrofitting services of Air Circuit Breakers (ACB’s) including the following:

  • A detailed site survey to determine all requirements and equipment required
  • Removal and complete installation of the new ACB’s with solid copper busbar
  • Retaining or improving fault level integrity
  • On-site testing and commissioning

All of these services allow for minimal operational downtime for the plant. Please forward your enquiries to ACDC Dynamics provides the innovative TemPower 2 “DoubleBreak” contact solution.

The innovative design eliminates any need for an intermediate flexible conductor in the moving contact assembly double arc chambers, while dissipating all arc energy within it’s structure.

The internally symmetrical “DoubleBreak” structure means the moving contact is isolated from the supply voltage, even when the ACB is reverse connected. The TemPower 2 Air Circuit Breakers (ACB’s) product range, offers Icu = Ics = Icw (for 1 second). This guarantees discrimination or selectivity.

Retrofitting refers to the addition of new technology to older systems. Retrofit ACBs can replace ageing, unsafe switches and circuit breakers.
Top 5 reasons to use Retrofit
  1. Improve safety and functionality
    • Modern circuit breakers offer safer interlocks, remote switching and circuit monitoring
  2. Optimise existing plant
    • Static components in a switchboard (the steelwork and busbar system) can be retained. Only the functional, moving parts (the circuit breakers) are replaced. Retrofitting is typically 80% cheaper than switchboard replacement with minimum downtime.
  3. Guaranteed spares available
    • Terasaki guarantee spare parts availability for at least 10 years after the withdrawal from sale of a circuit breaker.
  4. Modernise the protection system
    • Old protection relays can be removed and replaced with modern microprocessor protection which is integral to the ACB. It is then easier to interface the ACB with automatic plc controls.
  5. Reduce arc flash hazard
    • Modern ACBs clear short-circuits much faster than older types. This means that the incident arc energy is correspondingly lower.
Retrofit Services
We prefer to conduct a site survey for every retrofit project - even if the breaker to be replaced is already on our design database. This ensures that the installation is as quick as possible, with minimum disruption to the client’s supply.
 Mechanical and electrical interfaces are modelled using state-of-the-art 3-D CAD.

Manufacture, assembly and routine testing is carried out at Terasaki’s facility in Glasgow, Scotland. The factory and processes are certified to the ISO 9001 quality management standard.


We design retrofit ACBs on request. If you are interested in a brand which is not shown below we would be happy to examine it. New designs are continually added to our portfolio.

Check the latest list on the Terasaki website:

  • Terasaki
  • Ellison
  • GEC
  • Merlin Gerin
  • Siemens
  • Unelec
  • Square D
  • Mitsubishi
  • Sace • ABB
  • Hyundai
  • AEG • English Electric
  • MEM
  • Klockner Moeller
Some of our Retrofit designs can be installed without a shutdown. Where this is not possible, our team will ensure that disruption is minimised.