7.2 Selecting a Braking Resistor
7-13
Chap. 7 SELECTING OPTIMAL MOTOR AND INVERTER CAPACITIES
7.2 Selecting a Braking Resistor
7.2.1 Selection procedure
The following three requirements must be satisfied simultaneously:
1) The maximum braking torque should not exceed values listed in Tables 6.7 to 6.9 in Chapter 6, Section
6.4.1 [1] "Braking resistors." To use the maximum braking torque exceeding values in those tables,
select the braking resistor having one class larger capacity.
2) The discharge energy for a single braking action should not exceed the discharging capability (kWs)
listed in Tables 6.7 to 6.9 in Chapter 6, Section 6.4.1 [1] "Braking resistors." For detailed calculation,
refer to Section 7.1.3.3 "Heat energy calculation of braking resistor."
3) The average loss that is calculated by dividing the discharge energy by the cyclic period must not
exceed the average loss (kW) listed in Tables 6.7 to 6.9 in Chapter 6, Section 6.4.1 [1] "Braking
resistors."
7.2.2 Notes on selection
The braking time T
1
, cyclic period T
0
, and duty cycle %ED are converted under deceleration braking
conditions based on the rated torque as shown below. However, you do not need to consider these values
when selecting the braking resistor capacity.
Figure 7.11 Duty Cycle
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