DOC-0017-04-EN: AC20 Series - Hardware Installation Manual
DOC-0017-04-EN-A 22.03.2023
65 (154)
Dynamic Brake Resistor Protection Current Calculation:
𝐼𝐼𝑃𝑃𝐼𝐼𝐼𝐼𝑡𝑡
=
√𝑃𝑃𝑡𝑡𝐼𝐼𝑛𝑛𝑡𝑡
𝑅𝑅𝑅𝑅𝑡𝑡
× 1.1
Where:
Iprot
= Resistor Protective Current (A)
Pcont
= Continuous Braking Power (W)
Rdb
=
Dynamic Braking Resistor (Ω)
Dynamic Brake Resistor Peak Current Calculation:
𝐼𝐼𝑃𝑃𝑃𝑃
=
𝑉𝑉𝑅𝑅𝑡𝑡
𝑅𝑅𝑅𝑅𝑡𝑡
Where:
Ipk
= Dynamic Brake Resistor Peak Current (A)
Vdb
= Dynamic Brake Resistor Threshold Voltage (V):
382V
(230V products)
/
764V
(400V products)
Rdb
= Dynamic Braking
Resistor (Ω)
Dynamic Brake Resistor Peak Instantaneous Power Calculation:
𝑃𝑃𝑃𝑃𝑃𝑃𝑖𝑖𝑛𝑛𝑃𝑃𝑡𝑡
=
𝑉𝑉𝑅𝑅𝑡𝑡
²
𝑅𝑅𝑅𝑅𝑡𝑡
Where:
Ppkinst
= Dynamic Brake Resistor Peak Instantaneous Power (kW)
Vdb
= Dynamic Brake Resistor Threshold Voltage (V):
382V
(230V products)
/
764V
(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 10,000V/
µ
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:
1ø, 230V Products
Frame
Size
Product Code
Motor
Power
(kW)
Inductance
(mH/phase)
Rated Current
(A)
Peak Output
Current (A)
2
20G-12-0070...
1.5
1.208
7.0
13
20G-12-0100...
2.2
0.845
10
19
Notes:
- AC Motor Choke inductance values calculated @230V, 50Hz
- AC Motor Choke impedance is nominally 2% of drive rating
- AC Motor Choke maximum voltage rating should be 240V +10%, TN/IT
- AC Motor Choke frequency of operation is 0 – 120Hz
- AC Motor Choke inductance at peak current should be >85% of its nominal value