Type test – The four motors have the same design, same electrical and mechanical characteristic. Therefore, one motor has performed the required type test items. And these four motors have performed the routine test items. The two small integrated motors are separately driven fan motors for inner and outer ventilation to guarantee sufficient airflow to cool down the motors during operation. That they are powered up separately.The supply voltage for these 2 fans should be provided separately. The motors are crucial for the operation temperature. If one of them is found fautly, we should recommend it should be replaced with accordingly. Keeping a spare part should be considered by CEM.