The main function of the hydraulic oil pump motor is to generate driving torque as a power source for electrical appliances or various machinery. The motor and electrical control technology are inseparable, both in learning and work should be kept in mind. Today, Dalan Motor Editor compiled 10 important knowledge points for your reference.
1. Low-voltage electrical appliances
Refers to electrical appliances that play a role in making, breaking, protecting, controlling or regulating in circuits with an AC rated voltage of 1200V and a DC rated voltage of 1500V and below.
2. Zero pressure protection
In order to prevent the motor from starting automatically when the power supply is restored after the power grid is lost, it is called zero-voltage protection.
3. Undervoltage protection
When the power supply voltage drops below the allowable value, in order to prevent the control circuit and the motor from working abnormally, measures need to be taken to cut off the power supply, which is undervoltage protection.
4. Variable pole speed regulation
In asynchronous motor speed regulation, the speed regulation method of changing the number of stator pole pairs.
31. Frequency control
In the asynchronous motor speed regulation, the speed regulation method of changing the power frequency.
6. The principle of three-phase asynchronous motor energy consumption braking
Energy consumption braking is when the motor stops cutting off the three-phase power supply of the stator winding, the stator winding is connected to the DC power supply, and generates a static magnetic field. The interaction between the rotor induced current and the static magnetic field generates a braking torque for braking.
7. The working principle of the reverse connection braking of the three-phase asynchronous motor
Reverse braking is to change the phase sequence of the three-phase power supply 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 quickly stopped by the braking torque in the opposite direction of the rotation.
8. What is the difference between short circuit protection and overload protection?
The circuit will produce a large short-circuit current and electromotive force during short circuit and damage electrical equipment. Need to cut off the power quickly. Commonly used short-circuit protection components are fuses and automatic switches.
The motor is allowed to be overloaded for a short time, but long-term overload operation will cause the temperature rise of its winding to exceed the allowable value, and the motor must be powered off to protect the motor. A commonly used overload protection element is a thermal relay.
9. When the motor starts, the current is very large. Why doesn't the thermal relay act?
Due to the thermal inertia of the thermal element of the thermal relay, it will not be deformed quickly. The current is large when the motor is started, and the starting time is short. The large current is not enough to deform the thermal element and cause the contact to act.
10. In what situations are the three-phase AC motor reverse connection braking and energy consumption braking applicable?
Reverse connection braking is suitable for small capacity motors under 10KW that do not brake frequently. Energy consumption braking is suitable for larger capacity motors that require smooth, accurate braking and frequent starting.
----- Responsible Editor: Dalan Oil Pump Motor 02-Procurement Consultant
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