In addition to the function that regulates speed, the inverter also encompasses a safeguard function for the motor.
The inverter is a controlling mechanism that oversees the motor’s operation and entails various protection functions for the motor.
Most of the inverters include functions that shield against over-voltage, under-voltage, over-current, and overload.
The function that protects against over-current can be activated during any phase of motor acceleration, deceleration, and constant speed operation.
When the instantaneous value of the inverter output current exceeds the current detection value due to short-circuits at the output end or motor over-current, the over-current safeguard function comes into effect by enforcing motor shutdown, hence safeguarding the motor.
The voltage abnormal protection function has two cases.
The first case is overvoltage protection, which takes effect when the motor’s regenerative voltage increases, thereby reaching the overvoltage detection value of the main circuit’s DC voltage.
However, the protection cannot be implemented effectively if the input side of the inverter mistakenly receives too high voltage.
The second case is the undervoltage protection function, where the protection mechanism operates when the power supply voltage drops, causing the DC voltage of the main circuit to decrease to the undervoltage detection value.
If the instantaneous power failure restart function is activated, the power supply automatically resets, and no alarm signal is outputted when the power supply is restored for restarting.
If the voltage value drops to a point where the inverter control circuit voltage cannot be maintained, all protection function actions will reset automatically.
When the motor current exceeds the set value of the electronic thermal overload relay, the protection function operates, which is the motor overload protection function.
Some inverters can only protect specific motor types, while others may not provide excellent protection for other motors. Therefore, it is vital to verify the issue thoroughly during inverter modeling.
Additionally, when one inverter drives multiple motors, each motor must be equipped with its thermal overload relay.
In actual application, it has been observed that different brands of inverters offer diverse functions and varying control and protection effects for motors.
To guarantee the safety of motor operation and the overall operational effectiveness, it is imperative to choose and match an ideal inverter.
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