What is electrical discrimination?
Discrimination is the practice of selecting protective devices and adjusting their settings in order to limit interruption to electrical installations under fault conditions.
What does a MCB protect against?
MCBs or Miniature Circuit Breakers are intended to give protection against overloads and short circuits, which can cause damage to cables and equipment. MCBs have current ratings (6A, 10A etc.) above which they will start to open or trip and give protection to the equipment.
What are the limitations for MCB?
Disadvantages of MCBs: The cost of the MCB is greater than the fuse. The cost of the MCB distribution board is greater than the rewireable fuse board. The risk of overloading of the circuit due to unqualified of the person operating than completing removed.
What is fuse discrimination?
Discrimination is achieved if the total let-through energy of the circuit-breaker is less than the pre-arcing energy of the fuse, at all values of fault level.
What is MCB discrimination?
Discrimination is partial if the value short-circuit current on circuit F1 exceeds the short-circuit trip-current setting of circuit-breaker F9. For this maximum condition, both F1 and F9 will trip.
Does MCB protect from electric shock?
A Miniature Circuit Breaker is an electromechanical device designed to protect an electric circuit from over-current – A term to describe an electrical fault caused by either overload or short circuit. It is important to note that MCBs do not protect humans against electrical shock caused by ‘earth leakage’.
What is a Type B MCB used for?
‘B’ Curve MCB is used for the protection of circuits with equipment that does not cause surge current, like lighting and distribution circuits. So they are, the best fit for residential applications and domestic appliances with mainly Resistive Load.
What will be the disadvantages for not using the MCB?
- Slow tripping.
- Aging and wear.
- Vulnerability to heat.
- They are more expensive than fused switches.
- Can not protect against earth faults.
What is MCB and its advantages?
Miniature Circuit Breakers (MCBs) are electromechanical devices which are used to protect an electrical circuit from an overcurrent. The lead reasons for an overcurrent could be a short circuit or overload. Unlike a Fuse, MCB does not have to be replaced every time after a fault occurs and it can be reused.
What is fusing factor?
Fusing factor. It is the ratio of minimum fusing current and current rating of the fuse. Minimum fusing current is the minimum value of current due to which fuse melts. The current rating of fuse is the maximum value of current due to which fuse does not get melt.
Is it possible to discriminate between MCB’s?
Discrimination between mcb’s is typically hard to achieve. Having two in series like you have on this job is poor design. IIRC the the upstream MCB would roughly need a current rating of around 100A to discriminate with the 16A MCB if they are both type B…
When does discrimination occur in a circuit breaker?
Discrimination is the coordination between the operating characteristics of circuit breakers placed in series. When the fault occurs in system only the circuit breaker placed immediately upstream of the fault will trip. Discrimination as per IEC 60947-2 can be defined as follows:
What does discrimination in Eaton series G MCCB mean?
Eaton.Series G MCCB- accessories plug-in. Discrimination (or selectivity) is the selection of protective devices so that the device nearest to a fault will operate rather than any upstream device. The purpose is to ensure that the fault is isolated and supply is maintained to other parts of the installation without disruption.
Is the category a-MCCB intended for discrimination?
Category A – MCCBs are energy-limiting devices which are not specifically intended for discrimination under short-circuit conditions.