The basic principles and working process of motor protection device

Update date:2018-01-15 Source:maxge

Because the electric motor causes overload, phase failure, interlayer short circuit and short line, coil grounding leakage, transient over voltage caused by the inflow of damage, or due to mechanical causes, such as blocking, the rotation of the motor body have solid, due to lack of lubrication oil bearing wear or thermal conduction the phenomenon of damage to the motor. Due to the non normal operation or stop or damage may result in loss of production or stop time of human losses can not be compared with the motor itself, the cost of replacement, the loss is huge, so we need to protect the motor, so as to ensure the normal operation of production.

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For electrical failure, whether it is over current or over voltage, it is mainly due to the instantaneous increase of current and the damage of motor load current. According to this principle, motor protector can protect motor by monitoring the current value change of two phase (three phase) line of motor. For over voltage and low voltage, motor protection is achieved by detecting voltage change between motor phases.

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Its basic principles and working process:

 The sensor will change current of the linear motor protector to reflect the sampling port, after rectifying and filtering process, the DC voltage signal is converted into proportional to the motor current to protect the corresponding part with the given parameters were compared by single chip processing, processing circuit, drive power loop, so that the relay action.

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When the motor is driven in part due to overload resulting in current increases, the voltage signal from the current sensor will increase, the voltage value is greater than the protection setting value, work overload circuit, RC delay circuit after a certain delay (adjustable), drive outlet relay, contactor cut off main circuit. The working principles of under voltage and phase protection are basically the same.

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