What is Point On Wave (POW) Controller?
Point-on-Wave (controlled switching equipment) is utilized in GIS (Gas-Insulated Substations) to enhance circuit_breaker operations and reduce switching-related transients. This is critical for ensuring smooth, reliable, and effective CB operations while lowering electrical stresses, improving power quality, & extending equipment life.
Advantages of POW Controller
1). Reduced Switching Transients & VFTO (Very Fast Transient Overvoltages)
GIS substations are susceptible to VFTO because of their compact design & steel casings. POW relays guarantee that breakers operate at specific points in the AC waveform, reducing transients and safeguarding the insulation and attached equipment.
2). Reduction of inrush & outrush currents
Uncontrolled switching while energizing (or) de-energizing transformers, reactors, (or) capacitor banks can result in excessive inrush or outrush currents. Controlled switching mitigates these impacts by closing (or) opening the breaker at the optimum waveform point.
3). Extending Equipment Lifespan
Circuit breakers in GIS substations handle high system voltages and currents. Repeated transient stress can damage breaker connections. POW relays improve the reliability & longevity of GIS components such as breakers and transformers by decreasing switching surges.
4). Enhanced power quality and stability.
Switching transients may result in voltage fluctuations, harmonics, & system instability. Controlled switching ensures that processes run smoothly, hence enhancing power quality & network stability.
5). Reduced Breaker Restrike & Reignition Events.
Uncontrolled circuit breaker opening can cause insulation damage. POW relays allow for controlled opening at zero current, reducing the risk of restrikes.
6). Protection for Sensitive Equipment
GIS substations frequently serve critical loads including industrial plants, hospitals, & data centers. Reducing transient and inrush currents provides stable operation and protects sensitive downstream equipment.
Applications for GIS substations
1). Transmission line switching (OHL and cable feeders)
2). Transformer switching (decreased inrush currents)
3). Reactor switching (limiting transient overvoltages).
4). Switching capacitor banks (to avoid voltage spikes).