MVAW11B1AB9007A Auxiliary variable speed relay ALSTOM

Relay characteristics of relays

Input signal x of the relay increases continuously from zero to the action value xx when armature starts to draw. Output signal of the relay immediately jumps from y=0 to y=ym, that is, normally open contact from off to on. Once the contact is closed, the input x continues to increase and the output signal y will not change. When the input x drops from a value greater than xx to xf, the relay begins to release and the normally open contact is disconnected. We call this characteristic of relay as relay characteristic, also called input-output characteristic of relay.

1. Working principle and characteristics of relay (relay)

1. Working principle and characteristics of electromagnetic relay

Electromagnetic relays are generally composed of iron core, coil, armature, contact reed and so on. As long as a certain voltage is added to both ends of the coil, a certain current will flow through the coil, resulting in electromagnetic effect. Under the action of electromagnetic force attraction, the armature will overcome the tension of the return spring and draw towards the core, thus driving the moving contact and static contact (normally open contact) to draw. When the coil is powered off, the electromagnetic suction also disappears, and the armature will return to its original position in the spring’s reaction force, so that the moving contact and the original static contact (normally closed contact) release. This suction, release, so as to achieve the purpose of conduction in the circuit, cut off. For the “normally open, normally closed” contact of the relay, can be distinguished in this way: the relay coil is not energized when the static contact is disconnected, called “normally open contact”; A static contact in the switched state is called a “normally closed contact”.

2. Circuit principle

2.1 Brief introduction of relay

Relay is a kind of contact (or circuit) that connects or breaks AC-DC small capacity control loop when the input changes to a certain value

MVAW11B1AB9007A

2.2 Working Principle

The permanent magnet keeps the release state, and when the working voltage is added, the electromagnetic induction makes the armature and the permanent magnet produce attraction and repulsion torque, resulting in downward motion, and finally reach the suction state.

3, transistor drive drive circuit

3.1 Schematic diagram of circuit

NPN triode is recommended when transistors are used to drive relays. The specific circuit is as follows:

Brief introduction of working principle

When the input high voltage level, the transistor T1 saturation conduction, relay coil energized, contact suction.

When the input low level, the transistor T1 cut-off, relay coil power, contact disconnected.

3.2 Functions of each component in the circuit

Transistor T1 is the control switch. Resistor R1 mainly acts as a current limiting function to reduce the power consumption of transistor T1. Resistor R2 gives transistor T1 a reliable cutoff. Diode D1 continues in reverse to provide a drain path in the relay coil when the triode switches from on-on to off-off, and clamp its voltage to +12V.

4, integrated circuit drive circuit

Integrated circuits with multiple driving transistors have been used to simplify the design process of printed boards that drive multiple relays. Now we use the drive relay integrated circuit mainly TD62003AP.

When the input end of 2003 is high voltage level, the corresponding output outlet is low, both ends of the relay coil are energized, and the relay contacts are drawn. When the input end of 2003 is low voltage, the corresponding output outlet is in a high resistance state, both ends of the relay coil power off, and the relay contact is disconnected.