Foreword
The sealed relay is a kind of relay with a sealed structure that can prevent the external environmental influences on its interior and thereby improve the reliability and stability of the relay. With the widespread application in so many different industries, power, communication, transportation, and other fields, the sealed relay has very high market demand.
Basic sealed relay theory
A relay is an electrical control device that can realize the automatic and remote control of a circuit. It mainly consists of an input circuit, an output circuit, and an intermediate amplification circuit. When the input circuit receives a controlling signal, it will be amplified by the middle amplification circuit and drive the output circuit to conduct a switch action.
The sealed relay is one kind of relay that adds a sealing structure on the basis of ordinary relays in order to avoid the influence of the external environment on the interior of the relay. The sealed cavity can be made of a metal shell, plastic shell, or other material, filled with inert gas or vacuum inside in order to maintain moisture, dust, corrosive gases, etc. from corroding the interior of the relay.
Operating principle of sealed relay
They have the same principle of operation as ordinary relays, which is a magnetic induction-based principle. The signal input during the inênh circuit amplifies the middle-amplifying circuit and drives the coil to generate a magnetic field. The magnetic field acts on the armature, causing it to perform a sucking or releasing action that further drives the output circuit to achieve certain switch actions.
A sealed relay structure can avoid the external environment affecting the interior of the relay so that the reliability of the relay can be enhanced and its stability improved. For instance, under the conditions of high humidity, high temperature, and with corrosive gases, a sealed relay works normally but other ordinary ones do not work at all.
Classification of Sealed Relays
Sealed relays can be classified according to different standards, and common classification methods include the following:
- (1) Classified by coil voltage: It can be divided into DC sealed relays and AC sealed relays.
- (2) Classified by contact form: can be divided into unipolar single contact, unipolar double contact, bipolar single contact, bipolar double contact, etc.
- (3) Classified by contact load: can be divided into micro power, medium power, high power, etc.
- (4) Classified by sealing method: can be divided into metal shell sealing, plastic shell sealing, rubber sealing, etc.
Characteristics of Sealed Relay
Sealed relays have the following characteristics:
- (1) High reliability: this sealed structure can effectively avoid the external environment affecting the interior of the relay and improve the reliability of the relay.
- (2) Long service life: by way of sealing structures, sealed relays can serve longer and reduce maintenance costs.
- (3) High stability: even in severe environmental conditions, a sealed relay is still able to work normally and it has high stability.
- (4) Low noise: The sealing structure of sealed relay can reduce the noise made by relay during its switching process.
- (5) Miniaturization: Sealed relay uses a compact packaging design, with small volume that is convenient for installation and usage.
Relays Application
Sealed relays are widely applied to many industries, including power, communication, and transportation. Some common applications scenarios include the following:
- (1) Industrial automation control: Sealed relay can enable automatic and remote functions of industrial equipment for the improvement of production efficiency.
- (2) Power system: Sealed relays are used in power systems for functions like switching of circuit and protection.
- (3) Communications systems: Sealed relays could be utilized to perform on signal switching or amplification in communications systems.
- (4) Transport system: In transport systems, the application of sealed relays is intended to activate signal lights, switches, and other devices
- (5) Household appliances: Sealed relays are also utilized in the operation of household appliances to achieve automatic control and protection of electric circuits.
Selection of Sealed Relays
In the selection of a sealed relay, the following aspects should be considered:
- (1) Coil voltage: In the case of the voltage of the control circuit, select the corresponding sealed relay.
- (2) Contact form: In the use of control according to requirement, one chooses from single pole single contact, single pole double contact, double pole single contact, double pole double contact, etc.
- (3) Contact load: Select micro power, medium power, high power according to the magnitude of the load current.
- (4) Sealing method: Choose metal shell sealing, plastic shell sealing, and rubber sealing according to the usage environment.
- (5) Brand and quality: Select well-known brands and reliable sealed relays.
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Installation of sealed relay
The following attention should be paid when install the sealed relays:
(1) Installation environment: it should ensure that the environment is dry and clean with no corrosion gases
(2) Installation position: it should ensure that the sealed relay installation position is stable; avoid all kind of vibration and impact.
(3) Wiring method: according to the requirements set by the product manual, it should be wired correctly in order to ensure safety.
(4) Grounding: Good grounding should be ensured to avoid electromagnetic interference for the sealed relay.
Maintenance of sealed relays
In maintaining sealed relays, the following points should be observed:
(1) Regular check: Regularly check the working status of the sealed relay and handle abnormalities in a timely manner.
(2) Cleaning: Regularly clean the surface and contact points of the sealed relay to prevent dust from affecting performance.
The article reference comes from：Google patented sealed relay