Electrical transients in power systems can occur from a variety of sources and have a negative impact on the equipment and reliability of the power system. It is best to be aware of potential sources in your facility and to take precautions against them.
Electrical transients are sudden and short-lived surges of energy induced in power or data and communication lines in a utility or any facility. They have extremely high voltages that drive large amounts of current in an electrical circuit for periods ranging from less than a microsecond to several milliseconds. As a result, the system transitions from a stable to a momentarily disturbed state and back again. The steady-state condition refers to the stable state that exists after the transient has passed.
Most electrical transients are not of great magnitude, but their impact on the performance of circuits and interrupting or protective devices is critical. Transients in power systems take the path of least resistance to ground and can cause circuit components and semiconductor devices to overheat, resulting in malfunction and failure. Furthermore, a significant number of these electrical transients are large enough to cause the insulation of the power system’s equipment to fail.
During a transient, the adverse conditions can be extremely damaging to power system protection equipment and switchgear. Their impact on devices varies according to the device and its location on the power system. As a result, power system engineers constantly devise methods and means to limit the magnitude of transients produced and control their effects on operating equipment.
What Causes Transients In Power Systems??
There are various causes of power system transients; however, all of the ways and sources from which transients can originate can be classified as either internal or external sources.
An electrical system or facility is made up of numerous components and devices, both inside and outside of the utility grid. Transient voltages in electrical systems can be generated within the facility by inductive components such as transformers and motors. When the current flow in these devices is interrupted, the magnetic field collapses, resulting in voltage impulses or transients. The overall effect of these electrical transients is determined by several factors, including the location of the transient in the system, the size of the source, the time interval and rise time, the effect on nearby equipment, and the electrical system configuration. Internal sources do not generate large-scale surges. Experience has shown that transients caused by internal sources rarely cause the system voltage to exceed twice its normal value.
The following list contains several sources of transient voltages within a facility:
- Switching capacitors
- Interruption of current (motors, etc.)
- The operation of power electronics (SCRs, etc.)
- Welding by electrostatic discharge (Arc)
- Faulty wiring or a tripped circuit breaker
- Closed contacts and relays
- Loading or disconnecting
Although voltage transients occurring outside of the electrical system can have an impact on a facility’s operation, internal transient voltage occurrences and sources are more common. The normal operation of devices within the facility, such as motors, welding stations, electric furnaces, ovens, induction heaters, and so on, can cause voltage transients that affect adjacent equipment.
External to a facility, there are several sources of transient voltages:
- Switching a Lightning Capacitor
- Line/cable selection
- Switching a transformer
- Operation of a fuse that limits current
What are the types of Electrical Transients?
There are two types of transients, according to the IEEE 1159-2019 standard: impulsive and oscillatory.
An impulsive transient is defined as a sudden and non-power frequency change in voltage or current or both that is unidirectional in polarity. Lightning transients and electrostatic discharges are examples of impulsive transients.
An oscillatory transient is defined as a sudden and non-power frequency change in voltage, current, or both that is bidirectional in polarity. An example of a cause is the energizing of a capacitor bank or the switching of a cable.
What are the effects of Electrical Transients?
Voltage transients’ impact on electronic equipment generally falls into one of four categories:
- Sporadic interruption: When a transient event is injected into a data or control network, it causes data to be lost or corrupted. As a result, a load or device may lock up, trip, or operate incorrectly. This causes Sporadic Interruption.
- Chronic deterioration: Chronic deterioration can occur when a component’s integrity and reliability are eroded by a series of transient events. The cumulative effect of transient voltages over days, weeks, or even months leads to the eventual inoperability of the vulnerable component. Because the transient voltages are frequent and relatively consistent in this case, it is possible to pinpoint their origin.
- Inadvertent failure: Inadvertent or Latent failures are similar to chronic degradation in that they are caused by a significant transient event that damages components but not to the point where they can no longer perform their intended function. The ordinary stresses of normal operation result in the component’s inoperability overtime–again, days, weeks, or even months. This mode is more difficult to troubleshoot because the root cause of the failure could have occurred at an unknown time in the past.
- Cataclysmic failure: Cataclysmic or Catastrophic failures caused by transient voltages are easily identified and detected because the affected component or device ceases to function properly almost immediately and the damage may be visible. The transient’s voltage peak magnitude or rise rate exceeds the component’s rated threshold, resulting in a permanent open circuit or short circuit within the component. These types of events often correlate component failures with power system disturbances.
Microprocessors and programmable logic controllers (PLCs) are particularly susceptible to voltage transient damage. As a result, exposing these types of equipment to voltage transients can reduce their reliability and shorten their operational life. As technology advances and the scale of these devices shrinks, the device components become smaller, increasing their susceptibility to voltage transient damage.
Transient voltages have been shown to interfere with the normal operation of equipment, resulting in erratic behaviour and lower end-product quality. Furthermore, interruptions in continuous manufacturing processes can result in revenue losses due to downtime in production.
How do Electrical transient analysis services help in mitigating Transient issues?
Transient analysis is extremely useful for analyzing a circuit’s response to an alternating current or direct current driving voltage. Although most people will examine the frequency domain behaviour of a circuit driven by an AC source, it is difficult to examine the transient behaviour without additional calculations. Instead, you can use a SPICE simulator to examine the response in the time domain using transient analysis for circuits. Transient Services are performed along with Electrical Safety Audits.
Electrical Transient Analysis Services aids industries in:
- Determine the behaviour of the plant/system over its entire operating range: start-up, shutdown, and accident scenarios.
- Ensure proper design and material selections, which can result in significant cost savings in plant construction (avoid overly conservative approach).
- Combination of control and plant thermal-hydraulic simulation to determine if operating problems, such as emissions, control philosophy, and so on, exist.
- A good control strategy can help you save a lot of money on your operations (avoid an overly conservative approach).
- Design and optimise components to ensure optimal system behaviour, even when the system is not in use or is in a transient state.
- Simulations are used to design and commission control systems.
- Dynamic integrated simulations will identify bottlenecks, inefficiencies, and safety risks that steady-state simulations will miss.
SAS Powertech’s Electrical Transient Analysis Services are one of the best in India. SASPPL has been providing Electrical transient analysis services to its clients across various verticals in India & South East Asia Region. We are known for sharing findings transparently & unbiased reporting. Our Electrical Transient Analysis services and solutions are the most affordable, and we have helped clients achieve predicted results.