Danfoss FC 300 Programming Manual page 7

Introduction
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 frequency converter is connec-
ted to mains. 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 uninten-
ded start occurs, these stop functions are not
sufficient. In such cases the mains 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 compro-
mised (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 mains
supply connected, may start if faults occur in the
electronics of the frequency converter, 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
frequency converter are not sufficient. In such cases
the mains 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 Safe Stop section of the VLT
AutomationDrive FC 300 Design Guide.
4. Control signals from, or internally within, the
frequency converter may in rare cases be 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.
FC 300 Programming Guide
High Voltage
Touching the electrical parts may be fatal - even after
the equipment has been disconnected from mains.
Also make sure that other voltage inputs have been
disconnected, such as external 24 V DC, load sharing
(linkage of DC intermediate circuit), as well as the motor
connection for kinetic back up.
Systems where frequency converters 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
frequency converters 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 frequency converter 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 frequency converter 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 frequency
converter while re-establishing full control of the motor.
In hoist applications "Protection mode" is not usable because
the frequency converter will usually not be able to leave this
mode again and therefore it will extend the time before
activating the brake – which is not recommendable.
The "Protection mode" can be disabled by setting
par. 14-26 Trip Delay at Inverter Fault to zero which means that
the frequency converter will trip immediately if one of the
hardware limits is exceeded.
NOTE
It is recommended to disable protection mode in
hoisting applications (par. 14-26 Trip Delay at Inverter
Fault = 0)
®
MG.33.M9.02 - VLT is a registered Danfoss trademark
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