Theory:Time Relay Usage:Equipment running time control Protect Feature:Sealed Contact Load:High Power Color:Beige Shell material:Abs plastic Power supply:220VAC/380VAC
Time relay refers to a kind of relay whose output circuit needs to pass a specified accurate time to produce a jump change (or contact action) after adding (or removing) the input action signal. It is an electrical component used on lower voltage or lower current circuits to switch on or off higher voltage and higher current circuits.
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Time relays are a very important component in electrical control systems. In many control systems, time relays are required to implement time-delay control. Time relay is an automatic control appliance that uses electromagnetic principle or mechanical action principle to delay the closing or breaking of contacts. Its characteristic is that there is a delay from the time when the attraction coil obtains the signal to the contact action. Time relays are generally used to control the motor starting process as a function of time.
The main function of the time relay is as an execution device in simple program control. When it receives the start signal, it starts timing. After the timing is over, its working contacts open or close, thereby promoting the subsequent circuit work. Generally speaking, the delay performance of the time relay can be adjusted within the designed range, so that it is convenient to adjust its delay time. A single time relay may not be able to start delayed closing, and then close after a period of time, and then realize the delayed closing first and then the delayed opening, but generally speaking, by configuring a certain number of time relays and intermediate relays It can be done.
1) Keep the time relay clean, otherwise the error will increase.
2) Check whether the power supply voltage and frequency match the time relay voltage and frequency before use.
3) According to user requirements, select the length of the control time of the time relay.
4) For DC products, pay attention to the wiring according to the circuit diagram and pay attention to the polarity of the power supply.
5) Try to avoid use in places with obvious vibration, direct sunlight, moisture and oil contact.
1. Classification according to working principle According to different working principles, time relays can be divided into air damping time relays, electric time relays, electromagnetic time relays, and electronic time relays.
(1) Air damping time relay uses the principle of damping when air passes through a small hole to obtain a delay. Its structure is composed of three parts: electromagnetic system, delay mechanism and contacts. The electromagnetic mechanism is a double-port direct-acting type, the contact system is a micro-switch, and the delay mechanism uses an airbag damper.
(2) Electronic time relay The electronic time relay is based on the principle that the capacitor voltage in the RC circuit cannot jump, and can only be gradually changed according to the exponential law, that is, the resistance characteristic is obtained by the delay. Features: Wide delay range, up to 3600 S, high precision, generally about 5%, small size, impact shock resistance, easy adjustment.
(3) Motor-type time relay The motor-type time relay uses a micro-synchronous motor to drive the reduction gear train to obtain a delay.
Features: Wide delay range, up to 72 hours, delay accuracy up to 1%, and the delay value is not affected by voltage fluctuations and ambient temperature changes. The delay range and accuracy of the motor-type time relay is unmatched by other time relays. Its disadvantages are its complicated structure, large size, low life, expensive price, and accuracy is affected by the power frequency.
(4) Electromagnetic time relay. The electromagnetic time relay is made by using the principle that the magnetic flux slowly decays after the electromagnetic coil is powered off to delay the release of the armature of the magnetic system to obtain the delayed action principle of the contact. Its characteristic is that the contact capacity is large, so the control Large capacity, but small delay time range. The accuracy is slightly worse, mainly used in the control of DC circuits.
2. Classification by delay According to different delay methods, time relays can be divided into two types: power-on delay type and power-off delay type.
(1) The energized delay type time relay starts to delay immediately after obtaining the input signal. It needs to wait for the delay to complete, and the execution part outputs the signal to manipulate the control circuit; when the input signal disappears, the relay immediately returns to the state before the action .
(2) The power-off delay type time relay is the opposite. When the input signal is obtained, the execution part has an output signal immediately; and after the input signal disappears, the relay needs to go through a certain delay before returning to the state before the action.