Conditions and advantages and disadvantages of motor full voltage start

Full-voltage starting, also called direct starting, is a common starting method. It connects the stator winding of the motor directly to the power supply and starts at the rated voltage. It has the characteristics of large starting torque and short starting time. It is also simple, economical and reliable. Way of starting.

When the AC motor starts, the voltage on the power distribution bus should meet the following requirements:

◆ Under normal circumstances, when the motor is frequently started, it should not be lower than 90% of the rated voltage; when the motor is not started frequently, it should not be lower than 85% of the rated voltage.

◆ When no other electrical equipment is connected to the power distribution bus, it can be determined according to the conditions to ensure the starting torque of the motor; for low-voltage motors, the voltage of the contactor coil should not be lower than the release voltage.

◆ When the distribution bus is not connected with lighting or other loads sensitive to voltage fluctuations, and the motor is not started frequently, it should not be lower than 80% of the rated voltage.

The selection of the starting method of the cage motor and synchronous motor should meet the following requirements:

◆ When the following conditions are met, the motor should start at full pressure

◆ When the motor starts, the voltage of the power distribution bus should comply with the provisions of the "Code for Design of Power Distribution of General Electric Equipment".

◆ Mechanical can withstand the impact moment when starting at full pressure.

◆ The manufacturer has no special regulations on the starting method of the motor.

◆ When the conditions of full-voltage starting are not met, the motor should be started at a reduced voltage, or choose another appropriate starting method.

◆ When speed regulation is required, the starting mode of the motor should match the speed regulation mode.

Advantages and disadvantages of motor full voltage start

Full pressure starting is a commonly used starting method, also known as direct starting. It connects the stator winding of the motor directly to the power supply and starts at the rated voltage. It has the characteristics of large starting torque and short starting time. It is also a simple, economical and reliable starting method. At present, low-voltage cage motors designed and manufactured consider mechanical strength and thermal stability according to the impact torque and heating conditions during full-voltage starting, so as long as the equipment being towed can withstand the impact torque of full-voltage starting, If the pressure drop does not exceed the allowable value, you should choose the full-voltage starting method.

The disadvantage of full-voltage starting is that the starting current is large, which can reach 5 to 8 times the rated current. When the motor power is large and the power supply capacity is small, the starting current of the motor will cause the voltage of the distribution system to drop, thereby reducing This affects the quality of the power supply, especially for devices that are sensitive to voltage fluctuations