When overcurrent devices are selectively coordinated?

When overcurrent devices are selectively coordinated?

Two overcurrent devices are selectively coordinated when the downstream overcurrent device closest to the fault opens before the upstream overcurrent device can. Code Change Summary: The selective coordination requirements in Article 700 have been expanded.

What is selective coordination NEC?

Selective coordination is required for systems related to life safety (as defined in the NEC), and is achieved when an overcurrent on a circuit is interrupted and only the closest upstream device opens such that only the section of the electrical system with a problem is taken offline.

What is overcurrent coordination?

An overcurrent coordination study is the comparison and selection of operating times of the protective devices that achieve the objectives of the protection system under abnormal system conditions. This study should include all devices from the utilization equipment to the source.

Are circuit breakers overcurrent devices?

Even though fuses and circuit breakers will open the circuit during periods of overload, they are overcurrent devices because they are capable of interrupting short circuits.

What provides overcurrent protection?

Fuses, circuit breakers, or fusible links are the most commonly used methods to provide overcurrent protection to a circuit or the internal wiring of a piece of equipment. Breakers, fuses, and fusible links generally function as conductors and add a negligible amount of resistance to the total circuit.

What will circuit breakers do in the event of overcurrent condition?

In the event of an overcurrent situation, fuses will blow or circuit breakers will trip. Although these devices protect the circuit against overcurrent conditions, they only open the circuit and disconnect the supply of electricity.

How can we control over current?

Overcurrent protection is the method of implementing hardware and other electrical components to limit or disable current flow. Fuses, circuit breakers, or fusible links are the most commonly used methods to provide overcurrent protection to a circuit or the internal wiring of a piece of equipment.

Is non selective coordination A circuit condition?

This non-selective operation is normally the result of a medium to high level short circuit. This fault may be line-to-line, line-to-ground, or 3 phase bolted in nature. It is also possible that the non-selective OPENING could be due to overload conditions on the branch circuit.

What is a breaker coordination study?

A circuit breaker coordination study is used to analyze the tripping times for the series of overcurrent devices being compared, generally from the source through the largest branch circuit device.

What is the main disadvantage of current co ordination system?

The main disadvantage of this method of discrimination is that the longest fault clearance time occurs for faults in the section closest to the power source, where the fault level (MVA) is highest.

What causes overcurrent?

An overcurrent occurs when the current exceeds the rated amperage capacity of that circuit or of the connected equipment (such as an appliance) on that circuit. An overcurrent can be caused by overloading the circuit or by a short circuit, a ground fault, or an arc fault.

What causes overcurrent in a circuit?

What are the two types of overcurrent?

Types of Overcurrent. The three major categories or types of overcurrent are overload, short-circuit, and ground-fault.

What is non selective coordination?

A fault on a branch circuit opens protective devices “D”, “C” and “B.” The entire power supply to the building is completely shut off. This non-selective operation is normally the result of a medium to high level short circuit. This fault may be line-to-line, line-to-ground, or 3 phase bolted in nature.