Danfoss VLT AutomationDrive FC 301 Programming Manual page 9

Introduction
WARNING
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.
NOTICE
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.
NOTICE
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
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VLT AutomationDrive FC 301/302 Programming Guide
Protection Mode
Once a hardware limit on motor current or DC link voltage
is exceeded the frequency converter enters the Protection
mode. Protection mode means a change of the PWM
modulation strategy and a low switching frequency to
minimise losses. This continues for 10 s 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 usually is unable to leave
this mode again and therefore it extends the time before
activating the brake, which is not recommended.
Protection mode can be disabled by setting 14-26 Trip
Delay at Inverter Fault to zero which means that the
frequency converter trips immediately, if one of the
hardware limits is exceeded.
NOTICE
It is recommended to disable Protection mode in
hoisting applications (14-26 Trip Delay at Inverter Fault =
0)
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