Electromagnetic relay is a commonly used component in active control circuits. In fact, it is an active switch that controls a larger current with a smaller current. Therefore, it is widely used in electronic devices. Electromagnetic relays are generally composed of a coil, an iron core, and several sets of contact springs. There are two types of contact points: moving contact points and stationary contact points. Contact points that can move during operation are called moving contact points, while those that cannot are called stationary contact points.

The working principle of an electromagnetic relay is as follows: when the coil is energized, the iron core is magnetized to generate sufficient electromagnetic force, which attracts the armature and drives the spring, causing the moving contact and the stationary contact to close or separate; When the coil is powered off, the electromagnetic attraction disappears, the armature returns to its original position, and the moving and stationary contacts return to their original closed or separated state. When applied, as long as the circuit controlled by the demand is connected to the contact, the Xinchuangzhi relay can be used to achieve the intention of control.

Below is a brief introduction to the characteristic parameters, type symbols, and application criteria of electromagnetic relays.

Characteristic parameters: The primary characteristic parameters of electromagnetic relays are as follows:

1. Extra operating voltage or extra operating current: This refers to the voltage or current required by the coil during relay operation. The construction of a type of relay is generally the same. In order to adapt to circuit applications with different voltages, a type of relay typically has multiple additional operating voltages or currents, distinguished by standard types.

2. DC resistance: This refers to the DC resistance of the coil. Some product manuals provide additional operating voltage and DC resistance, in which case the additional operating current can be calculated based on Ohm's law. If the additional operating current and DC resistance are known, the additional operating voltage can also be calculated.

3. Pull in current: It refers to the small current that a relay can produce a pull in action. In practical applications, in order to make the relay reliably engage, the given voltage should be equal to or slightly higher than the additional operating voltage. Generally, it should not be greater than 1.5 times the additional operating voltage. Otherwise, it will burn out the coil.

4. Release current: It refers to the large current that causes the relay to release. If the current of a relay in the suction state is reduced, when the current decreases to a relative degree, the relay returns to its unpowered state, and this process is called the release action of the relay. The release current is much smaller than the pull in current.

5. Contact load: It refers to the voltage or current allowed by the relay contacts. It determines the extent to which relays can manipulate voltage and current. Relays with low contact loads should not be used to control high currents or voltages during application. For example, if the contact load of JRX-13F electromagnetic relay is 0.02A 12V, it cannot be used to control the on/off of 220V circuit.

Electrical symbols and contact methods of relays. The relay coil is indicated 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" for the relay inside or next to the rectangular box. There are two ways to indicate the contacts of relays: one is to directly draw them on one side of a rectangular box, which is more intuitive. Another method is to draw each contact separately into its own control circuit according to the requirements of circuit connection. Usually, the same text symbols are marked separately next to the contacts and coils of the same relay, and the contact groups are numbered to distinguish them. There are three basic ways for relay contacts:

1. When the coil is not powered, the two contacts of the dynamic type (H-type, overseas: A-type) are disconnected. After being powered on, the two contacts are closed. Indicate with the Pinyin prefix "H" of the compound character.

2. Dynamic break type (D type, foreign: B type): When the coil is not powered, the two contacts are closed, and when powered on, the two contacts are disconnected. Use the pinyin prefix "D" with a hyphen to indicate.

3. Conversion type (Z-type, foreign: C-type) This is a contact group type. This type of contact group has three contacts, with the center being the moving contact and one static contact on each top and bottom. When the coil is not powered, the moving contact and one of the stationary contacts are disconnected and the other is closed. After the coil is powered on, the moving contact moves, causing the originally disconnected to become closed and the originally closed to become disconnected, achieving the intention of transformation. This type of contact group is called a conversion contact. Use the pinyin prefix "z" of the character "zhuan" to indicate.

In addition, a relay can also have one or more contact groups, but all of them are limited to the above three methods. In circuit diagrams, the drawing of contacts and contact groups is required to be based on the condition when not powered.

Selection of Xinchuangzhi Relay:

1. First, understand the required conditions: ① the power supply voltage of the control circuit and the large current that can be supplied; ② Voltage and current in the controlled circuit; ③ How many sets of contacts are required for the controlled circuit and what type of contacts are needed. When selecting Xinchuangzhi relays, the power supply voltage of the general control circuit can be used as the basis for selection. The control circuit should be able to supply sufficient operating current to the Xinchuangzhi relay, otherwise the relay closing will be unstable.

2. After consulting relevant materials to determine the application conditions, you can search for relevant materials and find the type and standard number of the required relay. If you already have a relay on hand, you can check whether it can be used based on the materials. Then consider whether the size is suitable.

3. Pay attention to the volume of the tools. If used for general electrical appliances, in addition to considering the capacity of the chassis, the primary consideration for small Xinchuangzhi relays is the installation layout of the circuit board. For small appliances such as toys and remote control devices, ultra small relay products should be selected.

Article source: Zhongshan Relay Manufacturer www.jxzhongxuan.com