Danfoss VLT HVAC, Руководство по программированию

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sharing (linking of DC intermediate circuit) or
external 24V DC are installed. Check that all voltage
sources have been disconnected 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 frequency converter is
connected to mains. If personal safety consider-
ations (e.g. risk of personal injury caused by contact
with moving machine parts following an uninten-
tional start) make it necessary to ensure that no
unintended start occurs, these stop functions are
not sufficient. In such cases the mains supply must
be disconnected.
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 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.
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, these
control signals must not be relied on exclusively.
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 discon-
nected, such as load sharing (linkage of DC intermediate
circuit)
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.
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. Parameter
0-07 Auto DC Braking IT
may cause PWM when coasted.
Introduction VLT HVAC Basic Drive Programming Guide
10 MG.18.B1.02 - VLT
®
is a registered Danfoss trademark
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