RCCN WeChat QrCode
Mobile WebSiteStar connection: Three windings, one end connected to one phase of the three-phase voltage and the other end connected together.
Delta connection: Three windings are connected end to end, and three phases are connected to the three terminals.
Decompression start: When the motor capacity is large, the power supply voltage is lowered into the stator winding of the motor to start the motor.
Main circuit: The main circuit is a circuit from the power supply to the motor or the end of the line, which is a circuit through which a strong current flows.
Auxiliary circuit: auxiliary circuit is a small current through the circuit
Speed relay: A non-electrical signal detection device that uses a rotational speed as an input to output a switching signal when the measured rotational speed rises or falls to a predetermined set value.
Relay: A relay is a control element that uses a variety of physical quantities to convert a power or non-electricity signal into an electromagnetic force (with contact) or a step change in the output state (no contact)
Thermal relay: A protective device that works by the principle of the thermal effect of current.
AC relay: A relay that draws the coil current to AC.
Temperature relay: A protective device that operates by indirectly reflecting the winding temperature by means of a superheated element is called a temperature relay.
Jog circuit: press the jog button, the coil is energized, the main contact is closed, the motor is connected to the three-phase AC power supply, and the rotation is started; when the button is released, the coil is de-energized, the main contact is disconnected, and the motor is powered off. turn.
Variable pole speed regulation: In the speed regulation of asynchronous motor, the speed regulation method of changing the pole number of stator pole.
Frequency control: In the speed regulation of asynchronous motor, the speed control method of changing the power frequency.
The principle of energy consumption braking of three-phase asynchronous motor: energy braking is when the motor stops cutting the three-phase power of the stator winding, the stator winding is connected to the DC power supply, generates a static magnetic field, and uses the interaction between the induced current of the rotor and the static magnetic field. A braking torque is generated for braking.
The working principle of the reverse braking of the three-phase asynchronous motor: the reverse braking is to change the phase sequence of the three-phase power of the stator winding when the motor is stopped, so that the rotating magnetic field of the stator winding is reversed, and the rotor is subjected to the braking rotation opposite to the rotating direction. The moment acts to stop quickly.
What is the difference between short-circuit protection and overload protection: When a short circuit occurs, the circuit generates a large short-circuit current and electric power to damage the electrical equipment. Need to cut off the power quickly. Common short circuit protection components are fuses and automatic switches.
The motor allows short-term overload, but long-term overload operation will cause the winding temperature rise to exceed the allowable value, and also protect the motor from power failure. Commonly used overload protection components are thermal relays
When the motor starts, the current is very large. Why does the thermal relay not work: Because the thermal relay has thermal inertia, it will not deform quickly. When the motor starts, the current is very large, and the starting time is very short. The large current is not enough for heat. Component deformation causes contact action.
Commonly used relays are divided into several types according to the principle of operation: electromagnetic, magnetoelectric, inductive, electric, photoelectric, piezoelectric, time and temperature (thermal) relays, etc.
