EM500 Open-Loop Vector Control Inverter User Manual
382
If motor speed falls too fast or motor load shakes too frequently during inverter
running, then its electric potential energy will charge inner capacitor through inverter in a
reverse way, leading to the voltage pump up at both ends of power module, which easily
causes inverter to be damaged. Internal control of inverter can suppress this situation
based on load condition and when braking feature cannot meet the user demands, external
braking resistor is required to release energy timely. External braking resistor functions
for energy consumption brake, which will dissipate all the energy to power braking
resistor. So, select reasonable and effective power and resistance for the braking resistor.
The power of braking resistor is according to the following formula.
Pb (The power of braking resistor) = P (the power of inverter) * D (braking
frequency)
D - Braking frequency (estimated value)
Normally braking D = 10%
Occasionally braking D = 5%
Elevator braking D=10% ~ 15%
Lifting braking for height more than 100m D= 50% ~ 60
The table below for the EM500 series inverter is recommended rated power of
braking resistor which is for reference only (D=10% ~ 20%). If braking frequency is
lager the power of braking resistance should be larger.
Cable connected to
the resistor (mm
2
)
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