Resistor Braking; Overvoltage Control (Ovc); Dc Brake; Ac Brake - Danfoss iC7 Series Application Manual

Application Guide | iC7 Series Industry

Resistor Braking

2.5.2
In applications that require fast or continuous braking, a drive fitted with a brake chopper is typically used. Excess energy, generated by
the motor during the braking of the application, is dissipated in a connected brake resistor. Braking performance depends on the specific
drive rating and the selected brake resistor.
2.5.3

Overvoltage Control (OVC)

If braking time is not critical or the load is varying, the overvoltage control (OVC) feature can be used to control the stopping of the
application. The drive extends the ramp-down time when it is not possible to brake within the defined ramp-down period. This feature
must not be used in hoisting applications, high inertia systems, or applications where continuous braking is required.
2.5.4

DC Brake

When braking at low speed, the braking of the motor can be improved by using the DC brake feature. The software offers configurable
DC-braking for induction motor control. It injects a user-defined DC current.

AC Brake

2.5.5
In applications where the operation of the motor is non-cyclic, AC braking can be used to shorten the braking time. Excess energy is
dissipated by increasing losses in the motor during braking. Performance is motor type dependent and offers best performance on
asynchronous motors.

DC Hold

2.5.6
The software offers the possibility to configure the feature DC Start for DC holding before entering normal motor control.

Load Sharing

2.5.7
In some applications, 2 or more drives control the application at the same time. If 1 of the drives is braking a motor, the excess energy
can be fed to the DC link of a drive driving a motor, which results in a reduction of the total energy consumption. This feature is typically
useful in, for example, decanters and carding machines, where smaller power-sized drives operate in generator mode.
2.6

Protection Features

2.6.1

Grid Protection

The drive protects against conditions in the power grid that can affect proper operation. The grid is monitored for phase imbalance and
phase loss. When the imbalance exceeds specified limits, the drive issues a configurable response and corrective actions can be taken.
The supply frequency is also monitored, and when the drive is outside acceptable limits, it reacts in the configured way. Furthermore, the
software of the drive offers optional protection against undervoltage and a configurable response to grid spikes.

Drive Protection Features

2.6.2
The drive is monitored and protected during operation.
Inbuilt temperature sensors measure the actual temperature and provide relevant information to protect the drive. If the temperature
exceeds its nominal temperature conditions, derating of operational parameters is applied. If the temperature is outside the allowed
operating range, the drive stops operation.
The motor current is continuously monitored on all 3 phases. If there is a short circuit between 2 phases, or a fault to ground, the drive
detects the short circuit and immediately turns off. If the output current is exceeding its nominal values during operation for longer
periods than allowed, the overload capability is reduced until the conditions are restored.
The DC-link voltage of the drive is monitored. If it exceeds critical levels, the drive issues a warning. If the situation is not resolved, the
drive stops operation.
18 | © 2024.05
Industry Application Software Overview
AB480436531518en-000601 / 136R0283