MEJORING RELAY

~ a relay operates when the value of a quantity is more or less than a current value . the different types of measuring relay are as follow:

                                                             current relay

~ when the value of the current passing through the relay reaches the predetermined value , the current running to the relay is driven. these include overcurrent and undercurrent relay.

~ the relay operates when the cut value in the under current relay is less than currant extent.

                                                              power relay

~ power relay a relay that operates when the value of power is higher or lower than the predetermined value is called a power relay.

~ this relay can be of power or under power type.

                                                               voltage relay

~ a relay that operates when the value of voltage is higher or lower than the set value is called voltage relay.

~ these include over voltage and under voltage relays.

                                                             frequency relay

~ this type of relay operates when the value of the frequency increases or decreases fro  the predetermined value .

~ these include over frequency relay and under frequency relay and under frequency relay and under frequency relay and under frequency relay.

                                                           directional relay (AC)

~ this relay operates on a phase relation between alternating quantities. these include the following types

                                                        directional relay (DC)

~ this is how the current operates according to the directional. this is usually a permanent magnet moving coil type relay

                                                           differential  relay

~ this involves two or more winding and operates on a scalar and vector difference of two or more electrical quantities.

                                                         voltage unbalance relay

~ voltage unbalance relay this relay operates when the voltage of the polyphase system is unbalanced beyond the predetermined ratio.

                                                             time distance relay

~ this relay operates as a distance a but has a typhoid in proportion to the distance.