Kb-electronics KBWA-23D Manual do Utilizador descarregar pdf (Página 15)

If external fan cooling is provided, open ventilated motors can also achieve an

extended speed range at full rated torque. A box fan or blower with a minimum of

100 CFM per HP is recommended. Mount the fan or blower so the motor is

surrounded by the airflow. See Figure 4.

FIGURE 4

OPEN VENTILATED MOTOR WITH EXTERNAL FAN COOLING

4.4 ELECTRONIC MOTOR OVERLOAD PROTECTION

The drive contains Modified I

t Overload Protection (UL approved as an oveload

protector for motors). Part of this function consists of a Current Limit (CL) circuit,

which limits the drive current to a factory preset level of 160% of the rated drive

current. The CL Trimpot is used to recalibrate the drive current from 60% thru 190%.

The Power Start™ circuit provides an overshoot function that allows most motors to

develop more than 200% of starting torque and breakdown torque.

Standard I

t is undesirable because it causes nuisance tripping. It allows a very high

motor current to develop and will turn the drive off after a very short period of time.

KB's RMS Current Limit Circuit avoids this nuisance tripping while providing maximum

motor protection.

If the motor is overloaded to 120% of full load (75% of the CL setting), the I

t Timer

starts. If the motor continues to be overloaded at the 120% level, the timer will shut

down the drive after 30 minutes. If the motor is overloaded to 160% of full load, the

drive will trip in 6 seconds.

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