Over -current relay is divided into inductive electromagnetic and integrated circuits, which has the characteristics of time limit and reverse time limit. It is used in the main equipment such as motor, transformer and other main equipment, as well as the relay protection circuit of the transmission and distribution system.When the main device or transmission and distribution system occurs over load and short -circuit failure, the relay can reliable action or signal according to the scheduled time limit to ensure the safety of the main device and the transmission and distribution system.
Over -current relay choice
When choosing a current relay, you must first understand the basic conditions of related products.The first is the power supply voltage of the control circuit, especially for the maximum current that can be provided, which is very critical for choosing a product.Second, the current and voltage in the controlled circuit.In addition, it is necessary to understand how many groups and forms of contacts are needed.In addition, for the purchase of such products, try to choose professional manufacturers.Because after all, it is a device for electricity. If the quality parameters do not meet the standard, it will easily affect the use of related equipment.If the over -current relay is used on ordinary electrical products, the chassis volume and the circuit board installation and layout of the related device must be considered.
The role of over -current relay
The role and scope of over -current relay, the secondary loop protection device line of the electric power system involves the electrical protection device line, and is also used as an element startup component.Over -current relay is a startup element in the overload or short -circuit protection line of motors, transformers and transmission cables.Multifunctional AC relays that integrate overcurrent, speed break, delay, and execution.Electric power supply lines, transformers and motors in rural and cities electricity supply lines, transformers and motors.High accuracy, low energy consumption, accurate delay, high return coefficient, setting intuitive and convenient and other characteristics.Because of its wide range of use, it can work under 100-300V voltage conditions.If it provides a DC auxiliary power supply, it can completely replace the electromagnetic current relay, or it can also assist the power supply to use the switching power supply.Directly speaking, the role of current relay is to protect the electrical equipment from the impact of large currents, so that the electric equipment is separated from the grid during the effective time period.
Over -current relay parameter
Over -current relay is a tightly arranged iron wire on the iron core to form an electromagnetic magnet. When the coil is connected to the power, the current makes the core temporarily magnetic and has a certain strength magnetism. It can attract the iron hub to close the contact point.The rated operating voltage of the coil parameter allows the relay contact (the voltage is lower than that it cannot work) and the minimum coil voltage (test from small to large).Release current refers to the maximum current that can make relays work.When relay is at a time in the suction state, the current is reduced to a certain range, and the relay will return to an unpopular release state.At this time, the current is far less than the suction and the current
The return coefficient of over -current relay
The ratio of the return current to the action current is called the return coefficient, for example: 10A action, 8.9A return.The return coefficient is 8.9/10 = 0.89 The return coefficient shall not be less than 0.85.

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