What is a protective relay?
The protective relay is an electrical device used to protect circuits, equipment and operators from a number of undesirable electrical conditions by reducing the control circuit power when a failure is detected. These failure conditions include playback and voltage, frequency deviations and reversed power flows. The protective relay differs from the standard switching relays in that it is activated only when it is subjected to very closely defined input parameters. The protective relays are generally designed to respond to one particular anomaly, so most of the relay installations will usually contain banks of devices, each of which is devoted to a specific category of faults. Several mechanisms are used in the protective relay, including the fittings, induction disk and mechanisms moving coils.NG to the point where the loss or injuries of the device occurs. This applies especially to large industrial high -voltage and current installations where electrical failures often cause catastrophic damage to equipment or losson life. The protective relay is one such device with which it is commonly found in distribution and switching devices protecting devices from faults such as current and voltage overvoltage, frequency deviations and conditions of perverted energy flow.
This protection is achieved by routing the control circuit of installation through the protective relay contacts. During normal operation, contacts are closed, allowing the control circuit to remain active. If the relay sense the failure condition, activates, opens contacts and breaks the control circuit. This causes the installation and protection of the equipment and staff from damage or injuries in the process.
In some respects, the protective relay is similar to a conventional switching relay, with the main difference being the sensitivity of the mechanism operating a relay. The protective relays work subject to very specific parameters, while the general switching relay will be aboutto function in a relatively wide range of voltage and currents. In many cases, the operational parameters of the protective relay can be set to suit the surrounding conditions. This allows technicians to define specific characteristics conditions of the failure to which the relay responds.
Most protective relays are also designed to sense one category of errors, which only requires installation of several units to cover all potential errors. Several types of mechanisms are used in various types of protective relays, including mechanisms of induction disk, moving coils and anchors, each of which is suitable for specific conditions. Due to the critical role on the protection of the role, relay -beams play an electrical installation should be subject to strict maintenance and testing mode to ensure lasting accuracy and integrity.