Missing Motor Phase Detection; Line Phase Imbalance Detection; Switching On The Output; Overload Protection - Danfoss VLT AutomationDrive FC 301 Series Design Manual

Product Features
NOTICE!
AC brake is not as effective as dynamic breaking with a
resistor.
OverVoltage Control (OVC)
OVC reduces the risk of the adjustable frequency drive
4 4
tripping due to an overvoltage on the DC link. This is
managed by automatically extending the ramp-down time.
NOTICE!
OVC can be activated for PM motor with all control core,
plus
PM VVC , Flux OL and Flux CL for PM Motors.
NOTICE!
Do not enable OVC in hoisting applications.

4.1.3 Missing Motor Phase Detection

The Missing Motor Phase Function (4-58 Missing Motor
Phase Function) is enabled by default to avoid motor
damage in the case that a motor phase is missing. The
default setting is 1,000 ms, but it can be adjusted for a
faster detection.

4.1.4 Line Phase Imbalance Detection

Operation under severe line imbalance conditions reduces
the lifetime of the motor. Conditions are considered severe
if the motor is operated continuously near nominal load.
The default setting trips the adjustable frequency drive in
case of line imbalance (14-12 Function at Mains Imbalance).

4.1.5 Switching on the Output

Adding a switch to the output between the motor and the
adjustable frequency drive is permitted. Fault messages
may appear. Enable flying start to catch a spinning motor.
40
Design Guide

4.1.6 Overload Protection

Torque Limit
The torque limit feature protects the motor against
overload, independent of the speed. Torque limit is
controlled in 4-16 Torque Limit Motor Mode and or
4-17 Torque Limit Generator Mode and the time before the
torque limit warning trips is controlled in 14-25 Trip Delay
at Torque Limit.
Current Limit
The current limit is controlled in 4-18 Current Limit and the
time before the adjustable frequency drive trips is
controlled in 14-24 Trip Delay at Current Limit.
Speed Limit
Min. speed limit: 4-11 Motor Speed Low Limit [RPM] or
4-12 Motor Speed Low Limit [Hz] limit the operating speed
range to for instance between 30 and 50/60 Hz.
Max. speed limit: (4-13 Motor Speed High Limit [RPM] or
4-19 Max Output Frequency limit the max output speed the
adjustable frequency drive can provide.
ETR
ETR is an electronic feature that simulates a bimetal relay
based on internal measurements. The characteristic is
shown in Figure 4.1.
Voltage Limit
The inverter turns off to protect the transistors and the
intermediate circuit capacitors when a certain hard-coded
voltage level is reached.
Overtemperature
The adjustable frequency drive has built-in temperature
sensors and reacts immediately to critical values via hard-
coded limits.

4.1.7 Locked Rotor Protection

There may be situations when the rotor is locked due to
excessive load or some other factors (bearing, or
application create locked rotor situation). This leads to
overheating of motor winding (free movement of rotor is
required for proper cooling). The adjustable frequency
drive is able to detect the locked rotor situation with
open-loop PM flux control, and PM VVC
(30-22 Locked Rotor Protection).
Rev. 2014-04-04 All rights reserved.
plus control
MG33BF22