Parameters116 M-Max Series Adjustable Frequency Drive MN04020003E—October 2013 www.eaton.comBraking, continuedPNU IDAccessRUN Value/Range DescriptionFactory Setting(P1.3)P12.5 504 X — Brake chopper 00 Brake-chopper deactivated1 Automatic activation in operation (RUN)2 Automatic activation in operation (RUN) and upon stop (STOP)P12.6 1447 X — Brake chopper, DC bus switching threshold 7650–870V This function is only active with the three-phase frequencyinverters MMX34…3D3_ (3.3A) to MMX34…014_ (14A)The switching threshold for the brake transistor should alwaysbe above the maximum DC link voltageFor example, allowing for the maximum permissible inputvoltage peak of 10%:U LN = 400 VacU LN +10% = 400 Vac = 440 VacU DC = 1.35 x ULNmax = 1.35 x 440V = 594 Vdc (maximumpermissible DC link voltage in motor operation)Allowing for an energy absorption from the DC link of around30% during braking, the on threshold here for the brakingtransistor should be set to around 780VNote: Lower values for the on threshold will switch on thebraking resistor earlier so that it is subject to a greater loadThe DC link voltage is shown at M1.8. In practice, the value ofthe DC link voltage is around 565V at U LN = 400V
