166 Resistor brakingwhich two standard resistors are connected in parallel, two in series. The ER value ofthe four-resistor assembly is four times the value specified for the standard resistor. Selecting a custom resistorIf you use a resistor other than the default resistor, make sure that:1. The resistance of the custom resistor is greater or equal than the resistance of thedefault resistor in the rating table on page 169:where2. The load capacity of the custom resistor is higher than the instantaneous maximumpower consumption of the resistor when it is connected to the drive DC link voltage bythe chopper:where Selecting and routing the external brake resistor cablesUse the same cable type for the resistor cabling as for the drive input cabling to ensurethat the input fuses also protect the resistor cable. Alternatively, a two conductor shieldedcable with the same cross-sectional area can be used.R Resistance of the custom resistor.WARNING! Never use a brake resistor with a resistance smaller than Rmin.The drive and the chopper are not able to handle the overcurrent caused bythe low resistance.Rmin Resistance of the default resistorPr Load capacity of the custom resistorUDC Drive DC link voltage.1.35 · 1.25 · 415 V DC (when supply voltage is 380 to 415 V AC)1.35 · 1.25 · 500 V DC (when supply voltage is 440 to 500 V AC)R Resistance of the custom resistorR > RminPr > UDCR2
