About Circuit Breaker Testing
High voltage circuit breakers are extremely important for the function of modern electric power supply systems. The circuit breaker is the active link that ultimately has the role of operating the primary circuit when a fault has occurred. Circuit breaker testing should be performed at circuit breaker development, production and commissioning, plus during maintenance/fault tracing and after service (re-commissioning).
Why is Circuit Breaker Testing Important?
- Circuit breakers are employed to be the main protective unit for those high voltage assets within power systems
- They are the "extended arm" of relay protection trip contacts
- They give assurance that the breaker will operate when needed
Circuit Breaker Testing Includes:
- Insulation resistance test
- Contact resistance (SRM)
- Contact timing
- Travel (stroke, speed, damping, wipe)
- Operating coil current
Circuit breakers are some of the most important components in modern electric power systems. The circuit breaker has to operate within extremely tight tolerances when a disturbance is detected in the network to protect sensitive and costly assets such as transformers. They have to operate after months or in some cases after years of inactivity. To ensure proper function and optimise network reliability, reliable and efficient test instruments and methods are needed. New developments have made it possible to improve and re-evaluate conventional methods that sometimes involve time consuming and cumbersome process steps.
Why perform Circuit Breaker Testing?
Some of the most important of the many reasons for testing circuit breakers are to ensure they:
- Provide protection for expensive equipment
- Prevent outages that lead to loss of income
- Ensure reliability of the electricity supply
- Prevent downtime and darkness
- Verify breaker performance
Substation circuit breaker testing is an important task for any power utility because these breakers are there to facilitate the flow of current during normal operation and to interrupt current flow in the event of a fault.
All electrically operated devices are likely to experience some kind of failure in their lifetime (factors include ageing and external faults).
Keeping circuit breakers operating at peak performance is imperative and the Power Utility Operator has to be prepared and have a plan in place to handle every situation.
Utility companies generate, transmit and distribute power with the aim to do this with maximum availability, meaning losses should be kept to a minimum with acceptable levels of power quality and safety maintained. All this must be carried out in an environmentally friendly manner. Circuit breaker testing plays an important part in this goal.
Circuit breakers are the active link which ultimately has the role of quickly opening the primary circuit when a fault occurs. Often, the breaker has to perform its duty within tens of milliseconds, after months, and perhaps even years of idly being in circuit.
Since reliability centred maintenance (RCM) and condition based maintenance have become the established strategies for most owners and operators of electric power delivery systems, the need for reliable and accurate circuit breaker testing is clear.
Protection systems are put in place to detect all electrical faults or other abnormal operating conditions and they are coordinated to disconnect the smallest possible part of a power network in the event of a fault. With good system design, it should be possible to quickly restore normal operation. When a fault is detected by a protective relay and a trip impulse is sent to the breaker operating mechanism, the breaker has to function as specified and interrupt the current as soon as possible to prevent severe damage. The cost of damage caused by a malfunctioning circuit breaker can sometimes reach large sums.
Circuit breaker testing helps ensure proper functioning of a circuit breaker; a number of individual circuit breaker components that have to be calibrated and tested at regular intervals. The trigger for maintenance intervals differs greatly between power utilities but the intervals are often based on time since last test, number of operations, or severity of fault current operations. Environmental considerations such as humidity and temperature, whether the breaker is located in a desert or coastal region, also play into the maintenance scheme.
Mechanical wear and lubrication often affects the performance of breakers, so circuit breaker testing enables the operator to trend mission critical parameters and compare these with factory thresholds helps to verify proper breaker function.
If you have any questions contact our friendly team today - experts are here to advise on the full range of circuit breaker testing tools.