Motor current of the main circuit wires shall be not less than the rated current of the motor. When the motor is often close to full when conductor ampacity should be adequate margin. When the motor is working for short-time or intermittent work, wire should be made in a short time under load or intermittent load carrying capacity of not less than short-time of the motor operating current or rated load rate of the nominal current.
Second, the conductor of the main circuit of the motor should be mechanical strength and check voltage loss. Must ensure reliable line, still check wires under short circuit conditions of thermal stability.
Three, wound rotor motor rotor loop of the carrying capacity of the wire, should comply with the following requirements:
1. start brush is not short on time should not be less than the rated current of the rotor. When the motor for intermittent working, wires should be used under intermittent load carrying capacity.
2. the brushes shorting after starting, when the machine starting torque does not exceed the rated torque of the motor 50%, should not be less than the rated current of the rotor 35%; when the mechanical torque exceeds rated torque of the motor 50%, should not be less than the rated current of the rotor 50%.