MD380 User Manual Selection and Dimensions
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8.7.2 Selection of Power of Braking Resistor
In theory, the power of the braking resistor is consistent with the braking power. But in
consideration that the de-rating is 70%, you can calculate the power of the braking resistor
according to the formula 0.7 x Pr = Pb x D.
• Pr refers to the power of resistor.
• D refers to the braking frequency (percentage of the regenerative process to the whole
working process)
Application Elevator
Winding and
unwinding
Centrifuge
Occasional
braking load
General
application
Braking Frequency 20%–30% 20%–30% 50%–60% 5% 10%
Table 8-14 below provides data for reference. You can select different resistance and power
based on actual needs. However, the resistance must not be lower than the recommended
value. The power may be higher than the recommended value.
The braking resistor model is dependent on the generation power of the motor in the actual
system and is also related to the system inertia, deceleration time and potential energy
load. For systems with high inertia, and/or rapid deceleration times, or frequent braking
sequences, the braking resistor with higher power and lower resistance value should be
selected.
Table 8-16 Recommended values of braking resistor
Model
Recommended
Power
Recommended
Resistance
Braking Unit Remark
Single-phase 220 V
MD380S0.4GB 80 W ≥ 200 Ω
Built-in
(standard)
No special descriptionMD380S0.7GB 80 W ≥ 150 Ω
MD380S1.5GB 100 W ≥ 100 Ω
MD380S2.2GB 100 W ≥ 70 Ω
Three-phase 220 V
MD380-2T0.4GB 150 W ≥ 150 Ω
Built-in
(standard)
No special description
MD380-2T0.75GB 150 W ≥ 110 Ω
MD380-2T1.1GB 250 W ≥ 100 Ω
MD380-2T2.2GB 300 W ≥ 65 Ω
MD380-2T3.7GB 400 W ≥ 45 Ω
MD380-2T5.5GB 800 W ≥ 22 Ω
MD380-2T7.5GB 1000 W ≥ 16 Ω
MD380-2T11G 1500 W ≥ 11 Ω Built-in
(optional)
Add "B" to the model if a
braking unit is needed.
MD380-2T15G 2500 W ≥ 8 Ω
MD380-2T18.5G 3.7 kW ≥ 8.0 Ω External MDBUN-45-S
MD380-2T22G 4.5 kW ≥ 8 Ω External MDBUN-45-S
MD380-2T30G 5.5 kW ≥ 4 Ω External MDBUN-60-S
MD380-2T37G 7.5 kW ≥ 4 Ω External MDBUN-90-S
MD380-2T45G 4.5 kW x 2 ≥ 4 Ω x 2 External MDBUN-60-S x 2
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