What are the common types of relays? Look at the following Xiaobian AFE is how to introduce.
1 、 overcurrent relay
Over current relay, referred to as CO, is from the current exceeds the set value of the relay protection action, to do system lines and overload, is the most commonly used induction type current relay, the electromagnet and the rotating disk is the use of aluminum or copper, rely on the principle of electromagnetic induction to the disk rotating, in order to achieve the protective effect.
Induction type overcurrent relay is the use of current transformer two side current, in the relay to produce a magnetic field, in order to promote the disk rotation, but the flow of current must be greater than the current plate current value to rotate.
2, overvoltage relay overvoltage relay, referred to as OV, its main purpose is that when the abnormal voltage increase to 120% of the rated value of the system above, the action and the voltage relay circuit breaker protection of power equipment from damage, induction type structure and operation principle of voltage relay and the current relay is similar, only the main different circle.
3 、 under voltage relay
Undervoltage relay, referred to as UV, has the same configuration as an over voltage relay. Unlike the internal contacts and the applied voltage, the turntable rotates immediately.
4 、 earthing overvoltage relay
Grounding over voltage relay, referred to as OVG, or grounding alarm relay GR, the same structure as the overvoltage relay, and three-phase three wire non grounding system, connected to the earthing transformer open triangular grounding, used to detect zero phase voltage.
5 、 earthing overcurrent relay
Ground overcurrent relay, referred to as GCR, is a high-voltage line ground protection relay.
1) earthing overcurrent protection of high resistance grounding system;
2) earthing protection of generator stator winding;
3) inter layer short-circuit protection of split phase generator;
4) overheat protection of earthing transformer.
6 、 selective earthing relay
Selective earthing relay, referred to as SG, also referred to as directional earth relay (DG), is used in non earth system to protect the distribution line. Overhead lines and cable systems can also be used.
Selective grounding relay: the grounding voltage transformer zero phase sequence current detection in case of line grounding, selective grounding relay can actually said the fault line and the alarm, and in accordance with the need to select the fault line disconnect it, and continue to send electricity to the normal line.
7 phase lack relay
Open phase relay, referred to as OPR, or the lack of protection relay, referred to as PHR, in the three-phase circuit, when the power supply end of line breaker caused by single-phase, if not immediately cut off the line, will make the single-phase motor running and burning.
8, ratio differential relay ratio differential relay, referred to as RDR, is applied to transformer differential protection of AC motor, alternator, overcurrent protection relays have been used before, is an abnormal current flows through the equipment to protect the external fault generated, if the transformer, one or two side current unbalance or on current transformer characteristics is not the same, in these cases, this phenomenon will be extended several times, and the relay misoperation.