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Technical catalog for Susol & Metasol ACB
Technical catalog for Susol & Metasol ACB
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The recent development on low voltage protective device is on steady increase in quantity and high breaking
capacity achievement is on the way by breakthroughs in technology to accommodate larger power supply system.
Result from these process is a development of over 6000A product type and 150kA breaking capacity circuit
breaker to satisfy requests from bigger power supply system. In addition, when building a power distribution
system, it is critical to deliver and provide electricity to loads continuously along with maximum safe. To
accomplish these principles, necessity of protective coordination using proper protective devices is being
emphasized in the power system. When fault accident or overload conditions were detected by a protective
device, it should disconnect quickly from the accident area, yet continue to supply electricity to unharmed circuits.
It should also minimize damages on load machineries, and restore from the accident as soon as possible. In
general, methods that are implemented in low voltage system for short protection coordination are 1)fully rated,
2)discrimination, and 3)cascading. It is feasible to build economical and reliable low voltage distribution protection
system when these methods are properly implemented with loads substance and nature. Before proceed with
protective coordination explanations, structure of low voltage circuit breaker characteristic curve will be mentioned
first. Below picture 1 illustrates typical low voltage circuit breakers characteristic curve.
Mainly characteristic curve can be divided into two parts.
1. Overload Protection
Classify as long time delay area. Within this section, there are thermal and electronic types for MCCB. However
only the electronic type is available for ACB. And for thermal and electronic types have the same characteristics.
2. Short Protection
For electronic type case (include ACB), it is divided into short time delay and instantaneous operation area. For
thermal type case, there is only instantaneous operation area. When performing protective coordination, it is
guaranteeing that responsible breaker will operate according to its obligations under overload or short protection
area.
1. Protective Coordination
Picture1. Low Voltage Circuit Breakers Characteristic Curve
Long-time
Short-time
Instantaneous
Long-time
Threshold
Short-time
Threshold
Instant
Threshold
Override I
t
0.4ms
20ms
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