MSG11-5715-743/EN: AC20F Series - Hardware Installation Manual
MSG11-5715-743/EN 24.04.2023
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Dynamic Brake Resistor Protection Current Calculation:
𝐼𝑝𝑟𝑜𝑡 =
√𝑃𝑐𝑜𝑛𝑡
𝑅𝑑𝑏
× 1.1
Where:
Iprot
= Resistor Protective Current (A)
Pcont
= Continuous Braking Power (W)
Rdb
=
Dynamic Braking Resistor (Ω)
Dynamic Brake Resistor Peak Current Calculation:
𝐼𝑝𝑘 =
𝑉𝑑𝑏
𝑅𝑑𝑏
Where:
Ipk
= Dynamic Brake Resistor Peak Current (A)
Vdb
= Dynamic Brake Resistor Threshold Voltage (V):
382 V
(230 V products)
/
764 V
(400 V products)
Rdb
= Dynamic Braking
Resistor (Ω)
Dynamic Brake Resistor Peak Instantaneous Power Calculation:
𝑃𝑝𝑘𝑖𝑛𝑠𝑡 =
𝑉𝑑𝑏²
𝑅𝑑𝑏
Where:
Ppkinst
= Dynamic Brake Resistor Peak Instantaneous Power (kW)
Vdb
= Dynamic Brake Resistor Threshold Voltage (V):
764 V
(400V products)
Rdb
=
Dynamic Braking Resistor (Ω)
7.5
AC Motor Choke
The maximum rate of Voltage rise (dv/dt) present at the inverter output can be as high as 10,000 V/
s.
Adding an AC Motor Choke between the inverter output and motor:
1. Reduces the dv/dt and peak voltages present at the motor, which in turn reduces the stress applied
to the motor insulation.
2. Eliminates potential nuisance overcurrent trips in installations with long motor cable runs.
3. Limits parasitic capacitance flowing to earth.
Refer to ‘Chapter 11: Compliance’ for maximum motor cable lengths.
Where a choke is deemed necessary, Parker suggest the following AC Motor Choke ratings:
