About magnetic latching relay
Magnetic latching relay is a new type of relay developed in recent years, and it is also an automatic switch. Like other electromagnetic relays, it automatically turns on and off the circuit. The difference is that the normally closed or normally open state of the magnetic latching relay is completely dependent on the function of the permanent magnet, and the switching state of the magnetic latching relay is triggered by a pulse of a certain width.
Principle characteristics
Principle of action
The open and closed state of the magnetic latching relay is usually held by the magnetic force generated by the permanent magnet. When the contacts of the relay need to be opened or closed, only the positive (reverse) DC pulse voltage is used to excite the coil, and the relay completes the state transition between opening and closing in an instant. Normally, when the contact is in the holding state, the coil does not need to continue to be energized, and only the magnetic force of the permanent magnet can maintain the state of the relay.
Action process
When the contact of the relay needs to be set, it is only necessary to excite the coil J2 with a positive DC pulse voltage. The magnetic pole generated by the coil J2 after excitation interacts with the magnetic pole of the permanent magnet, and the same polarity repels each other and the different polarity attracts each other, making the relay The state transition from reset to set is completed in an instant.
Product parameter
Rated voltage
It refers to the voltage required by the coil when the relay is working normally. Depending on the model of the relay, it can be AC voltage or DC voltage.
DC Resistance
It refers to the DC resistance of the coil in the relay, which can be measured by a multimeter.
Pull-in current
It refers to the minimum current that the relay can produce a pull-in action. In normal use, the given current must be slightly larger than the pull-in current, so that the relay can work stably. As for the working voltage applied to the coil, generally do not exceed 1.5 times the rated working voltage, otherwise it will generate a larger current and burn the coil.
Release current
It refers to the maximum current that the relay generates to release the action. When the current in the pull-in state of the relay is reduced to a certain extent, the relay will return to the unpowered release state. The current at this time is much smaller than the pull-in current.
Switch voltage and current
Refers to the voltage and current allowed by the relay. It determines the magnitude of the voltage and current that the relay can control, and this value cannot be exceeded during use, otherwise it is easy to damage the contacts of the relay.
test
Measuring contact resistance
Use the resistance profile of a multimeter to measure the resistance of normally closed contacts and moving points. The resistance value should be 0, (the contact resistance can be measured in a more accurate way within 100 milliohms); while normally open contacts and moving points The resistance of a point is infinite. It can be distinguished which is a normally closed contact and which is a normally open contact.
Measuring coil resistance
The resistance value of the relay coil can be measured with the universal meter R×10Ω, so as to judge whether the coil is open.
Pull-in voltage and current
Find an adjustable regulated power supply and an ammeter, input a set of voltage to the relay, and connect an ammeter in the power supply loop for monitoring. Slowly increase the power supply voltage. When you hear the pick-up sound of the relay, write down the pick-up voltage and current. For accuracy, you can try several times and find the average.
Release voltage and current
The connection test is also like the above. When the relay is closed, the power supply voltage is gradually reduced. When you hear the relay releasing sound again, write down the voltage and current at this time. You can also try several times to get an average release. Voltage and release current. Under normal circumstances, the release voltage of the relay is about 10-50% of the pull-in voltage. If the release voltage is too small (less than 1/10 of the pull-in voltage), it cannot be used normally, which will threaten the stability of the circuit. , The work is unreliable.
Contact form
The relay coil is represented by a rectangular box symbol in the circuit. If the relay has two coils, draw two parallel rectangular boxes. At the same time, mark the text symbol "J" of the relay in or beside the long box. There are two ways to represent the contacts of the relay: one is to draw them directly on the side of the long box, which is more intuitive. The other is to draw each contact into its own control circuit according to the needs of circuit connection. Usually the same text symbols are marked next to the contacts and coils of the same relay, and the contact groups are numbered. To show the difference.
effect
Relay is an automatic switching element with isolation function, which is widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment, and is one of the most important control elements.
Relays generally have a sensing mechanism (input part) that can reflect certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, light, etc.); there is a mechanism (input part) that can realize "communication" and "connection" to the controlled circuit The actuator (output part) of "off" control; between the input part and the output part of the relay, there is also an intermediate mechanism (drive part) for coupling and isolating the input, functional processing and driving the output part.
The relay has the following functions:
1) Expand the scope of control. For example, when the control signal of a multi-contact relay reaches a certain value, multiple circuits can be switched, disconnected, and connected at the same time according to different forms of contact groups.
2) Zoom in. For example, sensitive relays, intermediate relays, etc., with a very small control quantity, can control a circuit with a large power.
3) Integrated signal. For example, when multiple control signals are input to a multi-winding relay in a prescribed form, they can achieve a predetermined control effect after comparison and integration.
4) Automatic, remote control and monitoring. For example, the relay on the automatic device and other electrical appliances can form a program control circuit to realize automatic operation.
The factory specializes in the production of various time relays, electromagnetic relays, electronic relays, high power relays, liquid level relays, solid state relays, high power relays, small relays, timers, counters, relays, etc.
The relay is essentially an electrical appliance that transmits signals. It achieves different control purposes according to the input signal.
Relays are generally used to switch on and off control appliances (motors)
For example, the current relay in a DC motor, when the current is too small or too large, it will control the start and stop of the motor after detecting this current signal
There are also thermal relays, such as when the motor is overloaded for a long time and the temperature is too high, it controls the motor to stop.
