Magnetic holding relay is a new type of relay developed in recent years. It is also an automatic switch. Like other electromagnetic relays, they can automatically turn on and off the circuit. The difference is that the normally closed or normally open state of the magnetic holding relay completely depends on the function of the permanent magnetic steel, and the switching state is triggered by the pulse electric signal of a certain width.

Principle characteristics

Action principle

The opening and closing states of the contacts of the magnetic holding relay are usually maintained by the magnetic force generated by the permanent magnet. When the contact of the relay needs to be in the open or closed state, it only needs to excite the coil with positive (negative) DC pulse voltage, and the relay completes the open and close state conversion in an instant. Usually, when the contact is in the hold state, the coil does not need to continue to be energized, and the state of the relay can be maintained only by the magnetic force of the permanent magnet.

Action process

When the contact of the relay needs to be set, only the positive DC pulse voltage needs to be used to excite the coil J2. The magnetic pole generated after the excitation of the coil J2 interacts with the magnetic pole of the permanent magnet. The same polarity repels each other and the different polarity attracts each other, so that the relay completes the state transition from reset to set in an instant.

Product parameters

Rated voltage

It refers to the voltage required by the coil when the relay works normally. Depending on the relay model, 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 multimeter.

Pull in current

It refers to the minimum current that the relay can produce pull in action. In normal use, the given current must be slightly greater than the pull-in current, so that the relay can work stably. Generally, the working voltage applied to the coil shall not exceed 1.5 times of the rated working voltage, otherwise a large current will be generated and the coil will be burned.

Release current

It refers to the maximum current that the relay generates release action. When the current in the pull in state of the relay decreases to a certain extent, the relay will return to the non energized release state. At this time, the current is far less than the pull-in current.

Switching voltage and current

It refers to the voltage and current allowed to be loaded by the relay. It determines that the relay can control the voltage and current, which cannot be exceeded when in use, otherwise it is easy to damage the contact of the relay.

test

Measuring contact resistance

Use the resistance gear of the universal meter to measure the resistance between the normally closed contact and the moving point, and the resistance value shall be 0 (the contact resistance value can be measured in a more accurate way within 100 milliohm); The resistance between the normally open contact and the moving point is infinite. Thus, it can be distinguished that it is a normally closed contact and that it is a normally open contact.

Measure coil resistance

Available universal meter R × Measure the resistance of the relay coil at 10 Ω gear to judge whether there is an open circuit in the coil.

Pull in voltage and current

Find the adjustable regulated power supply and ammeter, input a group of voltage to the relay, and connect the ammeter in series in the power supply circuit for monitoring. Slowly increase the power supply voltage. When you hear the pull-in sound of the relay, write down the pull-in voltage and current. For accuracy, you can try several more times to find the average value.

Release voltage and current

It is also a connection test as described above. After the relay is pulled in, gradually reduce the power supply voltage. When the release sound of the relay is heard again, record the voltage and current at this time. You can also try several more times to obtain the average release voltage and current. In general, 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 can not be used normally, which will threaten the stability of the circuit and unreliable operation.

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, the text symbol "J" of the relay shall be marked in or next to the rectangular box. There are two representations of relay contacts: one is to draw them directly on one side of the rectangular frame, 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 contact and coil of the same relay, and the contact group is numbered to show the difference.

effect

Relay is an automatic switching element with isolation function. It is widely used in remote control, telemetry, communication, automatic control, mechatronics and power electronic equipment. It is one of the most important control elements.

Relays generally have induction mechanism (input part) that can reflect certain input variables (such as current, voltage, power, impedance, frequency, temperature, pressure, speed, light, etc.); There is an actuator (output part) that can realize "on" and "off" control of the controlled circuit; Between the input part and the output part of the relay, there is also an intermediate mechanism (driving part) for coupling and isolating the input quantity, 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 multi contact relay reaches a certain value, it can change, disconnect and connect multiple circuits at the same time according to different forms of contact groups.

2) Zoom in. For example, sensitive relays, intermediate relays, etc. can control circuits with high power with a very small control quantity.

3) Integrated signal. For example, when multiple control signals are input into the multi winding relay in the specified form, the predetermined control effect can be achieved through comparison and synthesis.

4) Automatic, remote control and monitoring. For example, the relay on the automatic device, together with other electrical appliances, can form a program control circuit to realize automatic operation.

The factory specializes in producing all kinds of time relays, electromagnetic relays, electronic relays, high-power relays, liquid level relays, solid-state relays, high-power relays, small relays, timers, counters, relays, etc.

Relay is essentially a kind of electrical apparatus that transmits signals. It achieves different control purposes according to the input signals.

Relays are generally used to turn on and off control appliances (motors)

Such as the current relay in the 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 is also a thermal relay. When the temperature is too high due to long-term overload of the motor, it will control the motor to stop.

www.grinternational. Cn specializes in producing magnetic holding relay, high voltage DC relay, high voltage DC contactor, automobile relay, etc