Alpha 6000S series, Руководство пользователя

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Chapter 7 Peripheral Equipments
179
point be connected to the main control circuit.
In Table 7-4 are the guiding data. The user can select the different resistance values and power according to the
actual conditions (however, the resistance value cannot be less than the recommended value in the table, while the
power can be determined by referring to the calculation result). The braking resistor should be selected and
determined according to the generator power in the actual application system. It is related to the system inertia,
deceleration time, and potential energy load, etc, and should be selected according to the actual conditions. The
larger the system inertia is, the shorter the deceleration time required is, and the more frequent braking is, the
braking resistor with the larger power and the smaller resistance value should be selected.
Table 7-4 Motor power and brake resistor selection
Voltage (V)
Motor Power (kW) Resistance Value (Ω) Resistance Power (kW)
Single-phase 220
0.4 100 0.10
0.75 100 0.10
1.5 100 0.10
2.2 70 0.15
Three-phase 380
0.75 150 0.25
1.5 150 0.25
2.2 100 0.40
4 75 0.80
5.5 75 0.80
7.5 75 0.80
11 50 1.00
15 40 1.50
Notes: in this table, suggestions are only given for selection of the brake units installed inside the series of
frequency inverters (Type 3015GB and the below) with the same power grade. For Type 3018G and the above,
brake units should be installed additionally. The braking resistor should be selected by referring to the technical
specifications of braking unit and the following calculation method.
At braking, the regenerated energy of motor is almost consumed on the braking resistor. The braking power can be
calculated according to the following formula:
U
× U÷R = Pb
In the formula, R is the value of selected braking resistor, U is the braking voltage at stable braking of the system (it
varies with different systems; for the 380VAC system, it is generally taken as 700V), and Pb is the braking power.
Theoretically, the power of braking resistor is the same with the braking power, but generally 70% of it will be used.
Power required by the braking resistor can be calculated according to the following formula:
0.7
× Pr = Pb × D
In the formula, Pr is power of the braking resistor, and D is the braking frequency (proportion of the regeneration
process in the whole working process), which can be selected according to the following table:
Table 7-5 Reference for Braking Frequency
Application
Occasion Elevator Uncoiling &
Coil Taking Centrifuge Accidental
Braking Load General
Application
Braking
Frequency 20%~30% 20~30% 50%~60% 5% 10%
7.2.4 Leakage Protector
As there is direct earth safety capacitor or distributed capacitor inside the frequency inverter, the motor and with the
input & output lead wires, and the series of frequency inverters of the low-noise type, the higher carrier wave is used.
Thus, the earth leakage current of the frequency inverter is large, which is more obvious for the large-capacitor