If the pump motor is damaged, it may lead to paralysis of the entire system, bring immeasurable loss, so we must protect the motor when in use, in order to ensure the normal operation of the metering pump, dosing pump, motor protection machinery manufacturers introduced a metering pump from 12 aspects.

1. Overload protection

When the motor is in overload fault, long time exceeds its rated current operation, will lead to overheating, reduce insulation and burned, according to the characteristics of the motor protector heating, heat capacity calculation of motor, simulation of motor heating characteristics for the protection of the motor, the characteristics of different levels corresponding to the overload protection tripping

2, under load protection

When the motor load pump load, motor no-load or underload operation will cause harm, the protector provides underload protection, when the average percentage of three-phase current and rated current is lower than the set value, the protector should be in action (delay) set time in action or alarm in the alarm time.

3, plugging / blocking protection

In the motor starting or running, or if its reason due to the large mechanical overload caused by electric timing shaft is stuck, and did not promptly remove the fault, will cause motor overheating, insulation and reduce burning motor, blocking protection for starting this kind of failure to protect the motor, blocking protection applicable to protect the motor running in this kind of failure, when the current reaches the set current action, protector in action (delay) set time in action or alarm in the alarm time.

4. Fault (unbalance) protection

Phase (unbalanced) fault operation of the motor is of great harm, when the motor open phase or three-phase current imbalance, such as unbalanced rate of protection setting value, protection in accordance with the protection requirements set, stop or alarm instructions, to make the motor running safely.

5, grounding / leakage protection

The protector has the function of grounding protection and leakage protection at the same time. Vector and grounding current signal from the internal current transformer, short circuit protection for phase of the motor of the metal shell, the protector can increase the leakage current transformer, fault current detection of 30mA~50mA, mainly used for non direct grounding protection, to ensure the safety of the people.

6. External fault protection

When the protector is detected that there is an external fault, the external fault switch input is inconsistent with the input state of the switch defined by the protector, the protector is protected according to the set requirements, so as to ensure the safety of the motor device.

7, start over time protection

In the motor starting process, only has a phase interruption protector (unbalance), grounding / leakage protection function, the protection function does not work, in the end of starting, all protective functions (set by the user) are automatically input, when the motor starting time set the starting time is greater than the current user over. 1.1 times of rated current, protection in accordance with the protection requirements set, in action (delay) issued a stop command set time, stop the motor running.

8, phase sequence protection

A protector with phase sequence protection, when the voltage phase sequence of the power side of the power side is in accordance with the order of the set, the protector should not act. When the protector detects the error of the phase sequence of the electric D, the motor should not start.

9, undervoltage protection

Low voltage will cause the motor speed is reduced, or even stop running, when the voltage range of protection less motor running voltage drop to the set when the protector protection set according to the requirements in the action (delay) set time in action or alarm alarm in time, in order to avoid the production of important confusion, serious impact on production.

10. Overvoltage protection

The voltage is too high will damage the insulation of the motor, when the protector is set according to the requirements for protection voltage protection of motor voltage exceeds the set, in action (delay) set time in action or alarm alarm in time, to ensure the safety of motor equipment.

11, under power protection

The motor driving device damage, loss of mechanical output capacity, under load operation, the motor power factor is low, but the motor current, reactive power consumption of the system, when the percentage of load power and rated power is lower than the set action value, the protector in action (delay) set time in action or alarm in the alarm time in.

12. Overheating protection

The heat protection model of the motor is set up by mathematical method, and the heat protection of the low voltage motor is solved in principle.