Weq 105 A, Руководство пользователя

Страница: 31 / 91

Installation and Connection
3-14
3
3.2.3.2 Dynamic Braking
The braking torque that can be obtained from the frequency inverter without braking resistors varies from 10 %
to 35 % of the motor rated torque.
Braking resistors shall be used to obtain higher braking torques. In this case, the energy regenerated in excess
is dissipated in a resistor mounted externally to the inverter.
This type of braking is used in cases where short deceleration times are desired or when high inertia loads are
driven.
The “Optimal Braking” feature may be used with the vector control mode, which eliminates in most cases the
need of an external braking resistor.
NOTE!
Set P0151 and P0185 to their maximum values (400 V or 800 V) when using dynamic braking.
3.2.3.2.1 Sizing the Braking Resistor
The following application data shall be considered for the adequate sizing of the braking resistor:
- Desired deceleration time;
- Load inertia;
- Braking duty cycle.
In any case, the effective current value and the maximum braking current value presented in table 3.3 shall
be respected.
The maximum braking current defines the minimum braking resistor value in ohms.
The DC bus voltage level for the activation of the dynamic braking function is defined by parameter P0153
(dynamic braking level).
The power of the braking resistor is a function of the deceleration time, the load inertia, and the load torque.
For most applications, a braking resistor with the value in ohms indicated in table 3.3 and the power of 20 %
of the rated driven motor power. Use WIRE type resistors in a ceramic support with adequate insulation voltage
and capable of withstanding high instantaneous power with respect to rated power. For critical applications with
very short deceleration times and high inertia loads (ex.: centrifuges) or short duration cycles, consult WEG for
the adequate sizing of the braking resistor.