☑ Brake Resistor Sizing

An application requires a braking resistor rated 25 ohms with an average power during braking of 2500 watts. If you know your drive model number use the acs380 acs480 braking resistor specifications table and provide the values to request a quote.

Vw3a7732 Braking Resistor 28 Ohms 0 3 Kw Ip20

Dynamic Brake Calculator Kw Hp Resistor Regeneration

Resistance Is Not Futile Edelrid Ohm Assisted Braking

The braking resistor turns the stop energy into heat.

Brake resistor sizing. Calculating braking resistor power p p peak x duty cycle x 05 ppeak motor power rating x maximum torque x efficiency motor power rating. One joule is a very small quantity so we usually talk about kj or mj. This allows us to size a resistor perfectly fit for your application.

Use drive power rating if unknown maximum torque typically 100 to 200 use 15 if unknown motor efficiency typically 08 to 098 use 095 if unknown. To calculate the right size of the resistor you need the characteristic data of the load cycle. A braking resistor will compensate this energy and convert it to thermal energy.

Its the motors energy that needs to be dissipated and this will determine the resistors value. In order to design a braking system we have to consider both the amount of heat in joules and the rate at which it is generated. Thermal time constants in the order of 50 seconds and higher satisfy the criteria.

The only additional information we need from you is your required duty cycle or well assume its 50. Typical braking applications are intermittent d 1 the resistor should not be designed for continuous operation. It is important to correctly size a braking resistor.

Furthermore you need the brake power pbr and the minimum resistance value rmin which is defined by the vfd. Dynamic brake resistor has a large thermodynamic heat capacity then the resistor element will be able to absorb a large amount of energy without the temperature of the resistor element exceeding the operational temperature rating. Both types of energy are measured in joules j.

To compensate this the resistor must be bigger or use a heat sink. My guess is that your vfd would use the same value resistors. The duration of the braking period determines the temperature rise of the resistor as determined by the thermal time constant of the resistor manufacturer specified.

The duty cycle is 20 10 seconds on and 40 seconds off with a cycle time of 50 seconds. The teco manual calls for a 100 ohm 150 watt braking resistor for the 2hp unit a 70 ohm 200 watt resistor for the 3hp model. Brake time or duty cycle and the total cycle time.

Theyre pretty standard sizes. The lower the ohmic value of a resistor the faster it can stop the motor and the more heat it generates.