Resistor braking156A resistor other than the standard resistor can be used provided that:• its resistance is not lower than the resistance of the standard resistorWARNING! Never use a brake resistor with a resistance below the value specifiedfor the particular drive / brake chopper / resistor combination. The drive and thechopper are not able to handle the overcurrent caused by the low resistance.• the resistance does not restrict the braking capacity needed, ie,where• the heat dissipation capacity (ER ) is sufficient for the application, see step 3above.Placing the brake resistorsAll resistors must be installed outside the drive module in a place where they willcool and the maximum allowed cable length (10 m [33 ft]) is not exceeded.Arrange the cooling of the resistor in a way that:• no danger of overheating is caused to the resistor or nearby materials• the temperature of the room the resistor is located in does not exceed the allowedmaximum.Supply the resistor with cooling air/water according to the resistor manufacturer’sinstructions.WARNING! The materials near the brake resistor must be non-flammable. Thesurface temperature of the resistor is high. Air flowing from the resistor is ofhundreds of degrees Celsius. If the exhaust vents are connected to a ventilationsystem, ensure that the material withstands high temperatures. Protect the resistoragainst contact.Pmax Maximum power generated by the motor during brakingUDC Voltage over the resistor during braking, eg,1.35 · 1.2 · 415 V DC when supply voltage is 380 to 415 VAC1.35 · 1.2 · 500 V DC when supply voltage is 440 to 500 VACR Resistor resistance (ohm)Pmax < UDCR2
