WEG CFW500 V1.8X, Руководство по программированию, Страница: 145 / 172

Rheostatic Braking
CFW500 | 14-1
14
14 RHEOSTATIC BRAKING
The braking torque that may be obtained by the application of frequency inverters, without rheostatic braking
resistors, varies from 10 % to 35 % of the motor rated torque.
In order to obtain higher braking torques, resistors for rheostatic braking are used. In this case, the regenerated
energy is dissipated in the resistor mounted outside the inverter.
This kind of braking is used in cases where short deceleration times are desired or when high-inertia loads are
driven.
The Rheostatic Braking function can only be used if a braking resistor is connected to the inverter, and if the
parameters related to it are properly set.
P0153 – Rheostatic Braking Level
Adjustable
Range:
339 to 1200 V
Factory
Setting:
375 V (P0296 = 0)
750 V (P0296 = 1)
950 V (P0296 = 2)
Properties:
Access Groups
via HMI:
MOTOR
Description:
Parameter P0153 defines the voltage level to activate the braking IGBT, and it must be compatible with the
power supply.
If P0153 is set at a level too close to the overvoltage actuation level (F0022), it may occur before the braking
resistor can dissipate the motor regenerated energy. On the other hand, if the level is too lower than the
overvoltage, the function limits the actuation at a maximum of 15 % of the overvoltage level.
Thus, it is ensured that the braking resistor will not actuate in the DC link rated operating region; refer to Table
14.1 on page 14-1 . Therefore, although P0153 has a wide setting band (339 to 1200 V), only the values defined
by the actuation band in Table 14.1 on page 14-1 are effective, that is, values below the actuation band are
internally limited in the execution of the function and values above naturally deactivate the function.
Table 14.1:
Rheostatic Braking actuation value
Input Voltage Rated DC Link
P0153 Actuation
Band
P0153 Factory
Default
200 to 240 Vac 339 Vdc 349 to 410 Vdc 375 Vdc
380 to 480 Vac 678 Vdc 688 to 810 Vdc 750 Vdc
500 to 600 Vac 846 Vdc 850 to 1000 Vdc 950 Vdc
Figure 14.1 on page 14-2 shows an example of typical Rheostatic Braking actuation, where it can be observed
the hypothetical wave shapes of the voltage on the braking resistor and the voltage on the DC link. Thus, when
the braking IGBT connects the link to the external resistor, the DC link voltage drops below the value set by
P0153, keeping the level below fault F0022.