230 VAC User Manual

Operation

Dynamic braking

Dynamic braking may be used to rapidly stop a motor as shown in Figure 13 on

page 24. For the RUN/BRAKE switch, use a two-pole, two-position switch rated

for at least 250 VDC, 20 amps. For the dynamic brake resistor, use a 40-watt

minimum, high power, wirewound resistor.

Dynamic brake resistor value

Sizing the dynamic brake resistor depends on load inertia, motor voltage, and

braking time. Use a lower-value, higher-wattage dynamic brake resistor to stop a

motor more rapidly.

IMPORTANT: For motors rated 1/17 horsepower and lower, a brake resistor is not

necessary since the armature resistance is high enough to stop the motor without

demagnetization. Replace the dynamic brake with 12 gauge wire.

Table 2. Recommended Dynamic Brake Resistor Sizes

Motor Minimum Minimum

Armature Dynamic Brake Dynamic Brake

Current Rating Resistor Value Resistor Wattage

Less than 2 ADC 1 ohm 1W

2–3 ADC 5 ohm 5W

3–5 ADC 10 ohm 10W

5–10 ADC 20 ohm 20W

10–17 ADC 40 ohm 50W

ATTENTION: Wait for the motor to completely stop before switching it back

to RUN. This will prevent high armature currents from damaging the motor or

drive.

ATTENTION: Armature output can drift full ON with the switch in the

BRAKE position and will be driven full ON if the minimum speed option is

selected with the inhibit circuit. Failure to observe this precaution could result

in severe bodily injury or loss of life.