Danfoss VLT AutomationDrive FC 361 Series User Manual

3.2 Automated Operational Features
Automated operational features are active when the drive
is operating. Most of them require no programming or set-
up. The drive has a range of built-in protection functions
to protect itself and the motor when it runs.
For details of any set-up required, in particular motor
parameters, refer to the programming guide.
3.2.1 Short-circuit Protection
Motor (phase-to-phase)
The drive is protected against short circuits on the motor
side by current measurement in each of the 3 motor
phases. A short circuit between 2 output phases causes an
overcurrent in the inverter. The inverter is turned o when
the short circuit current exceeds the allowed value (Alarm
16, Trip Lock).
Mains side
A drive that works correctly limits the current it can draw
from the supply. Still, it is recommended to use fuses
and/or circuit breakers on the supply side as protection if
there is component break-down inside the drive (1
st
fault).
NOTICE
To ensure compliance with IEC 60364 for CE, it is
mandatory to use fuses and/or circuit breakers.
3.2.2 Overvoltage Protection
Motor-generated overvoltage
The voltage in the DC link is increased when the motor
acts as a generator. This situation occurs in the following
cases:
•
The load rotates the motor at constant output
frequency from the drive, that is, the load
generates energy.
•
During deceleration (ramp-down) if the inertia
moment is high, the friction is low, and the ramp-
down time is too short for the energy to be
dissipated as a loss throughout the drive system.
•
Incorrect slip compensation setting causing
higher DC-link voltage.
•
Back EMF from PM motor operation. If coasted at
high RPM, the PM motor back EMF can
potentially exceed the maximum voltage
tolerance of the drive and cause damage. To help
prevent this situation, the value of
parameter 4-19 Max Output Frequency is automat-
ically limited based on an internal calculation
based on the value of parameter 1-40 Back EMF at
1000 RPM, parameter 1-25 Motor Nominal Speed,
and parameter 1-39 Motor Poles.
The overvoltage can be handled either using a brake
function (parameter 2-10 Brake Function) and/or using
overvoltage control (parameter 2-17 Over-voltage Control).
Brake functions
AC brake is an alternative to improving braking without
using a brake resistor. This function controls an over-
magnetization of the motor when the motor is acting as a
generator. Increasing the electrical losses in the motor
allows the OVC function to increase the braking torque
without exceeding the overvoltage limit.
NOTICE
AC brake is not as eective as dynamic braking with a
resistor.
Overvoltage control (OVC)
By automatically extending the ramp-down time, OVC
reduces the risk of the drive tripping due to an
overvoltage on the DC link.
NOTICE
OVC can be activated for a PM motor.
NOTICE
Do not enable OVC in hoisting applications.
3.2.3 Missing Motor Phase Detection
The missing motor phase function (parameter 4-58 Missing
Motor Phase Function) is enabled by default to avoid motor
damage if a motor phase is missing. The default setting is
1000 ms, but it can be adjusted for faster detection.
3.2.4 Supply Voltage Imbalance Detection
Operation under severe supply voltage imbalance reduces
the lifetime of the motor and drive. If the motor is
operated continuously near nominal load, conditions are
considered severe. The default setting trips the drive if
there is supply voltage imbalance
(parameter 14-12 Response to Mains Imbalance).
3.2.5 Switching on the Output
Adding a switch to the output between the motor and the
drive is allowed, however fault messages can appear.
Product Overview and Featur... VLT® AutomationDrive FC 361
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Danfoss VLT AutomationDrive FC 361 Series Specifications

General

Brand	Danfoss
Model	VLT AutomationDrive FC 361 Series
Category	DC Drives
Language	English