trip unit MicroLogic 5.3 E for ComPacT NSX 630 circuit breakers, electronic, rating 630A, 3 poles 3d - C6335E630 (2024)

FAQs

What is the difference between a circuit breaker and a trip unit? ›

A trip unit, specifically, is the “brain” of the circuit breaker as its function is to measure physical parameters such as electrical current and decide when to “trip” or rapidly open the mechanical contacts of the circuit breaker. At the bare minimum, a trip unit needs to offer overload and short circuit protection.

Circuit breakers trip when there is too much electricity flowing through them or when they can no longer handle the excess current load. The breakers trip to turn off the power and cut off the flow of electricity to avoid problems that might exacerbate and cause more damage.

Some standard current ratings as defined in Indian Standards are: Low voltage circuit breakers (up to 1000V): 16A, 25A, 32A, 40A, 63A, 100A, 200A, 400A. Medium voltage circuit breakers (1kV to 52kV): 250A, 400A, 630A, 800A, 1250A, 1600A, 2000A, 2500A, 4000A.

Both thermal-magnetic and electronic trip circuit breakers can be tested for 100% ratings. although the trip characteristics of an electronic trip circuit breaker are not affected by ambient temperatures, the conductors are impacted by the temperature, thus the need for a special test for the 100% rating.

Micrologic trip systems use a set of current transformers (called CTs or sensors) to sense the current, a trip unit to evaluate the current m and a tripping solenoid to trip the circuit breaker. Micrologic trip-units are field-interchangeable.

(1) Overloaded Circuit

The most common cause of a circuit breaker tripping is too much current being drawn by lighting, devices or appliances on a given circuit, overloading it. Overloading wiring in a circuit generates immense heat, which can cause a fire.

Start by turning off all the lights, appliances, and electronic devices in your home. Then, reset the main circuit breaker by switching it off and on. Afterward, turn on each circuit one at a time, and observe which one trips the breaker. Once you've identified the circuit, you can focus on narrowing down the problem.

If your breaker keeps tripping, you need to address it immediately — ignoring the issue could result in major electrical damage, electrical shock, or even a fire.

A higher (AF) rating indicates a larger and more robust circuit breaker, capable of handling higher current loads without tripping. (AT) - Trip Unit Rating: The (AT) rating, on the other hand, represents the trip unit's settings within the circuit breaker.

This rating is labeled on the breaker itself. The standard for most household circuits are rated either 15 amps or 20 amps. An important note to remember is that circuit breakers can only handle about 80% of their overall amperage.

What is the trip threshold for a circuit breaker? ›

For all other shunt trips for legacy breakers (F, K, L, M, N, and P frames), the threshold is 75% of the rated voltage. For Powerpact and Masterpact breakers, the threshold is 70% of rated voltage.

The 80% rule says that no individual load shall exceed 80% of the branch circuit current rating. That reduces the probability of nuisance circuit breaker tripping. Nuisance tripping may tempt users to use extension cords on a continuous basis or otherwise engage in less safe usage practices.

Sections 210.19(A), 215.2 and 230.42(A) require the conductor to be sized no less than 100% of the noncontinuous load, plus 125% of the continuous load.

To be clear, a standard-rated breaker (also known as 80%-rated) does not mean it will trip at 80% of the current rating. All properly installed breakers are designed to carry 100% of their current rating for an indefinite period.

But there are switches that have a rated current trip point. So in reality it is two devices in one, a switch, and a circuit breaker. But they are not the sameas a circuit breaker.

What is a Trip Unit? A circuit breaker is an electrical switch designed to automatically detect and eliminate short circuits and overloads. The trip unit is the “brain” of the circuit breaker. It measures physical parameters such as current and decides when to “trip” or rapidly open the circuit breaker.

Should an overcurrent or short circuit occur in the electrical circuits, the Electronic Trip Unit will sense this abnormal condition and will send a signal to open (or to switch off) the CB thereby effectively isolating the abnormal condition.

Circuit breakers are switches that open when too much current flows through them. They're also more convenient because you can easily reset them when they trip. An electrical panel is typically larger than a breaker box and contains multiple breakers, fuses, and fuse boxes.