Protection Features; Monitoring Features - Danfoss iC2-Micro Anwendungshandbuch

iC2-Micro-Frequenzumrichter
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2.1.4.4 AC Brake
In applications with non-cyclic operation of the motor, AC braking can be used to shorten the braking time and is only supported
for asynchronous motors. Excess energy is dissipated by increasing losses in the motor during braking.
2.1.4.5 DC Hold
DC hold provides a limited holding torque on the rotor at standstill.
2.1.4.6 Load Sharing
In some applications, 2 or more drives are controlling 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, with a reduction of the total energy consumption. This feature is
useful in, for examples, decanters and carding machines, where smaller power sized drive operates in generator mode.

2.1.5 Protection Features

2.1.5.1 Grid Protections
The drive protects against conditions on the power grid that can affect proper operation.
The grid is monitored for phase imbalance and phase loss. If the imbalance exceeds internal limits, a warning is provided and the
user can initiate proper actions.
In case of an under- or overvoltage on the grid, the drive will provide a warning and stop operation if the situation remains or ex-
ceeds critical limits.
2.1.5.2 Drive Protection Features
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 tempera-
ture exceeds its nominal temperature conditions, derating will be applied. If the temperature is outside the allowed operating
range, the drive will stop operation.
The motor current is continuously monitored on all 3 phases. In case of a short circuit between 2 phases or a fault to ground, the
drive will detect this and immediately turn off. If the output current is exceeding its nominal values during operation for longer
periods than allowed, the drive will stop and report overload alarm.
The DC-link voltage of the drive is monitored. If it exceeds critical levels, a warning is issued and the drive will stop. If the situation is
not resolved, the drive will issue an alarm.
2.1.5.3 Motor Protection Features
The drive provides various features to protect the motor and the application.
The output current measurement provides information to protect the motor. Overcurrent, short circuit, ground faults, and lost mo-
tor phase connections can be detected and relevant protections initiated.
Monitoring of speed, current, and torque limits provides an additional protection of the motor and the application.
Locked rotor protection secures that the drive is not starting with a blocked rotor of the motor.
Motor thermal protection is provided either as a calculation of the motor temperature based on the actual load or by the means of
external temperature sensors, for example PTC.
2.1.5.4 Protection of Externally Connected Components
Externally connected options like brake resistors can be monitored.
Brake resistors are monitored for thermal overload, short circuit, and missing connection.
2.1.5.5 Automatic Derating
Automatic derating of the drive allows continued operation even if the nominal operation conditions are exceeded. Typical factors
affecting this are temperature, high DC-link voltage, high motor load, or operation close to 0 Hz. Derating is typically applied as a
reduction in switching frequency or change in switching pattern, resulting in lower thermal losses.

2.1.6 Monitoring Features

The drive offers a wide range of monitoring features providing information of operation conditions, grid conditions, and drive his-
torical data. Access to this information helps out analyzing operational conditions and identification of faults.
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