Warning Against Unintended Start; High Voltage; Protection Mode - Danfoss VLT AutomationDrive Programming Manual

Introduction
6. Do not remove the plugs for the motor and line
power supply while the Adjustable frequency
drive is connected to line power. Make sure that
the line power supply has been disconnected and
that the necessary time has elapsed before
removing motor and line power plugs.
7. Please note that the Adjustable frequency drive
has more voltage sources than L1, L2 and L3,
when load sharing (linking of DC intermediate
circuit) or external 24 V DC are installed. Make
sure that all voltage sources have been discon-
nected and that the necessary time has elapsed
before commencing repair work.

Warning against unintended start

1. The motor can be brought to a stop by means of
digital commands, bus commands, references or
a local stop, while the Adjustable frequency drive
is connected to line power. If personal safety
considerations (e.g., risk of personal injury caused
by contact with moving machine parts following
an unintentional start) make it necessary to
ensure that no unintended start occurs, these
stop functions are not sufficient. In such cases,
the line power supply must be disconnected or
the Safe Stop function must be activated.
2. The motor may start while setting the
parameters. If this means that personal safety
may be compromised (e.g., personal injury caused
by contact with moving machine parts), motor
starting must be prevented, for instance by use
of the Safe Stop function or secure disconnection
of the motor connection.
3. A motor that has been stopped with the line
power supply connected may start if faults occur
in the electronics of the Adjustable frequency
drive through temporary overload or if a fault in
the power supply grid or motor connection is
remedied. If unintended start must be prevented
for personal safety reasons (e.g., risk of injury
caused by contact with moving machine parts),
the normal stop functions of the Adjustable
frequency drive are not sufficient. In such cases,
the line power supply must be disconnected or
the Safe Stop function must be activated.
NOTE!
When using the Safe Stop function, always follow the
instructions in the section Safe Stop of the VLT
AutomationDrive Design Guide.
4. Control signals from or internally within the
Adjustable frequency drive may in rare cases be
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FC 300 Programming Guide

High Voltage

Touching the electrical parts may be fatal - even after the
equipment has been disconnected from line power.
Also make sure that other voltage inputs have been
disconnected, such as external 24V DC, load sharing
(linkage of DC intermediate circuit), as well as the motor
connection for kinetic backup.
Systems where adjustable frequency drives are installed
must, if necessary, be equipped with additional monitoring
and protective devices according to the valid safety
regulations, e.g., law on mechanical tools, regulations for
the prevention of accidents, etc. Modifications on the
adjustable frequency drives by means of the operating
software are allowed.
NOTE!
Hazardous situations shall be identified by the machine
builder/ integrator who is responsible for taking necessary
preventive means into consideration. Additional
monitoring and protective devices may be included, always
according to valid national safety regulations, e.g., law on
mechanical tools, regulations for the prevention of
accidents.
NOTE!
Crane, Lifts and Hoists:
The controlling of external brakes must always have a
redundant system. The Adjustable frequency drive can in
no circumstances be the primary safety circuit. Comply
with relevant standards, e.g.,
Hoists and cranes: IEC 60204-32
Lifts: EN 81

Protection Mode

Once a hardware limit on motor current or DC link voltage
is exceeded, the Adjustable frequency drive will enter
"Protection mode". "Protection mode" means a change of
the PWM modulation strategy and a low switching
frequency to minimize losses. This continues 10 sec after
the last fault and increases the reliability and the
robustness of the Adjustable frequency drive while re-
establishing full control of the motor.
In hoist applications, "protection mode" is not usable
because the Adjustable frequency drive will usually not be
able to leave this mode again and therefore it will extend
the time before activating the brake – which is not
recommended.
®
MG33MD22 - VLT is a registered Danfoss trademark
activated in error, be delayed or fail to occur
entirely. When used in situations where safety is
critical, e.g., when controlling the electromagnetic
brake function of a hoist application, these
control signals must not be relied on exclusively.
WARNING
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