Motor comprehensive protection can provide a full range of protection for the motor, the most basic protection includes overload protection, under-load protection, overheat protection, phase protection, phase sequence protection, under voltage protection, over-voltage protection, leakage protection and starting timeout protection and so on. So, where does this all come into play? How does it work?
Overload protection: when the motor is under the fault of overload and runs beyond its rated current for a long time, it will cause the motor to overheat, reduce the insulation and even burn out.At this time, the motor comprehensive protector will calculate the heat capacity of the motor according to the heating characteristics of the motor, and simulate the heating characteristics of the motor, so as to protect the motor. This protection mode is called overload protection.
Under-load protection: when the load carried by the motor is pump load, the motor will be damaged due to no load or under-load. The under-load protection function provided by the protector is that when the percentage of the average current of the three phases and the rated current is lower than the set value, the protector shall operate within the set time of the action (delay) or alarm within the alarm time. This kind of protection function, mainly in the pump equipment protection application.
Overheat protection: the overheat protection adopts the mathematical method to establish the heating model of the motor, which theoretically solves the problem of the low-voltage motor’s thermal protection.In general, the traditional thermal relay has this protection function.
Lack of phase protection: when the three-phase power supply current is unstable due to environmental factors, and one phase is disconnected or abnormal, the motor protector will detect the equipment lack of phase, thus acting for protection. Such protection behavior is lack of phase protection.
Phase sequence protection: protector with phase sequence protection functions, when the power supply side voltage and phase sequence in accordance with the order of the original set, protector will not move;The phase sequence of the motor when the motor protector detected by mistake, motor protector will response action, so that the motor can’t start.
Under-voltage protection: when the motor is running, the working voltage is too low, which causes the motor speed to decrease or even stop running. When the operating voltage of the motor drops to the set under-voltage protection range, the protector will protect according to the set requirements, operate within the set time of action (delay), or alarm within the alarm time, so as to avoid the confusion caused by the important production process and seriously affect the production.
Over-voltage protection: working voltage is too low will lead to fault, too high is no exception, will lead to motor insulation damage.When the operating voltage of the motor exceeds the set protection voltage, the protector will protect according to the set requirements, operate within the set time of the action (delay) or alarm within the alarm time to ensure the safety of the motor equipment.
Ground and leakage protection: the ground protection current signal is taken from the vector sum of the internal current transformer to protect the short circuit of the phase line against the metal outer box of the motor. Moreover, the protector can detect the fault current by increasing the leakage current transformer, which can be used for the equipment of indirect grounding protection, so as to ensure the personal safety of operators and improve the use safety of the equipment.
Starting timeout protection: during the starting process of the motor, the protector has the protection functions such as broken phase (three-phase unbalance) and earthing/leakage, while the other protection functions cannot play a protective role. Only at the end of the start, all the protection functions (according to the user’s actual Settings) will be automatically put into the protection work. And starting overtime protection, is to point to exceed the user when the motor starting time actually set the starting time, and when the current is greater than 1.1 times the rated current, the Integrated motor protector take protection work in accordance with the requirements of the set, in action (delay) setting time parking warnings, so that the motor stops running, corresponding fault protection equipment.
Of course, these basic functions are not every motor integrated protector will have in one. At present on the market, the function classification of a lot of motor protector is more fine, also more. There are a variety of protective functions of the protector, there are only a protective function of the protector. When the user is in the choice, can according to oneself actual demand, the choice is single function, if have a variety of protection demand, also can choose a variety of functions to gather in an organic whole synthesis protector.
Post time: Mar-03-2020