Danfoss VLT FC 103, Руководство по конструкции

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2.7 Fault, Warning and Alarm Functions
The frequency converter monitors many aspects of system
operation including mains conditions, motor load, and
performance, as well as frequency converter status. An
alarm or warning does not necessarily indicate a problem
with the frequency converter itself. It may be a condition
outside of the frequency converter that is being monitored
for performance limits. The frequency converter has various
pre-programmed fault, warning, and alarm responses.
Select additional alarm and warning features to enhance or
modify system performance.
This section describes common alarm and warning
features. Understanding that these features are available
can optimise a system design and possibly avoid
introducing redundant components or functionality.
2.7.1 Operation at Overtemperature
By default, the frequency converter issues an alarm and
trip at overtemperature. If
Autoderate and Warning is
selected, the frequency converter warns of the condition
but continues to run and attempt to cool itself by first
reducing its switching frequency. Then, if necessary, it
reduces the output frequency.
Autoderating does not replace the user settings for
derating for ambient temperature (see
chapter 5.4 Derating
for Ambient Temperature ).
2.7.2 High and Low Reference Warning
In open-loop operation, the reference signal directly
determines the speed of the frequency converter. The
display shows a flashing reference high or low warning
when the programmed maximum or minimum is reached.
2.7.3 High and Low Feedback Warning
In closed-loop operation, the frequency converter monitors
the selected high and low feedback values. The display
shows a flashing high or flashing low warning when
appropriate. The frequency converter can also monitor
feedback signals in open-loop operation. While the signals
do not affect the operation of the frequency converter in
open loop, they can be useful for system status indication
locally or via serial communication. The frequency
converter handles 39 different units of measure.
2.7.4 Phase Imbalance or Phase Loss
Excessive ripple current in the DC bus indicates either a
mains phase imbalance or a phase loss. When a power
phase to the frequency converter is lost, the default action
is to issue an alarm and trip the unit to protect the DC bus
capacitors. Other options are to issue a warning and
reduce output current to 30% of full current or to issue a
warning and continue normal operation. Operating a unit
connected to an imbalanced line may be desirable until
the imbalance is corrected.
2.7.5 High Frequency Warning
When staging on additional equipment such as
compressors or cooling fans, the frequency converter can
warn when the motor speed is high. A specific high
frequency setting can be entered into the frequency
converter. If the output exceeds the set warning frequency,
the unit shows a high frequency warning. A digital output
from the frequency converter can signal external devices
to stage on.
2.7.6 Low Frequency Warning
When staging off equipment, the frequency converter can
warn when the motor speed is low. A specific low
frequency setting can be selected for warning and to stage
off external devices. The unit does not issue a low
frequency warning when it stops nor after start-up until
after the operating frequency has been reached.
2.7.7 High Current Warning
This function is similar to high frequency warning, except a
high current setting is used to issue a warning and stage
on additional equipment. The function is not active when
stopped or at start-up until the set operating current has
been reached.
2.7.8 Low Current Warning
This function is similar to low frequency warning (see
chapter 2.7.6 Low Frequency Warning ), except a low current
setting is used to issue a warning and stage off equipment.
The function is not active when stopped or at start-up
until the set operating current has been reached.
2.7.9 No Load/Broken Belt Warning
This feature can be used for monitoring a no-load
condition, for example a V-belt. After a low current limit
has been stored in the frequency converter, if loss of the
load is detected, the frequency converter can be
programmed to issue an alarm and trip or to continue
operation and issue a warning.
Product Overview Design Guide
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