Rheostatic Braking - WEG CFW501 V1.8X Programming Manual

13 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 339 to 1200 V
Range:
Properties: V/f, V V W
Access groups MOTOR
via HMI:
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
on page 13-1. Therefore, although P0153 has a wide setting band (339 to 1200 V), only the values defined by the
actuation band in Table 13.1: Rheostatic braking actuation value on page 13-1
the actuation band are internally limited in the execution of the function and values above naturally deactivate the
function.
Input Voltage
200 to 240 Vac
380 to 480 Vac
500 to 600 Vac
Figure 13.1: Rheostatic braking actuation curve on page 13-2
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.
Table 13.1: Rheostatic braking actuation value
P0153 Actuation
Rated DC Link
339 Vcc 349 to 410 Vcc
678 Vcc 688 to 810 Vcc
846 Vcc 850 to 1000 Vcc
shows and example of typical DC braking actuation,
Rheostatic Braking
Factory
Setting:
Table 13.1: Rheostatic braking actuation value
are effective, that is, values below
P0153 Factory
Band Default
375 Vcc
750 Vcc
950 Vcc
375 V
(P0296 = 0)
750 V
(P0296 = 1)
950 V
(P0296 = 2)
13
CFW501 | 13-1