Danfoss VLT FC 103, Руководство по конструкции

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voltage before the drop-out and the motor load
determines how long it takes for the frequency converter
to coast.
Configure the frequency converter( parameter 14-10 Mains
Failure ) to different types of behaviour during mains drop-
out,
•
Trip lock once the DC link is exhausted.
•
Coast with flying start whenever mains return
(
parameter 1-73 Flying Start ).
•
Kinetic back-up.
•
Controlled ramp down.
Flying start
This selection makes it possible to catch a motor that spins
freely due to a mains drop-out. This option is relevant for
centrifuges and fans.
Kinetic back-up
This selection ensures that the frequency converter runs as
long as there is energy in the system. For short mains
drop-out, the operation is restored after mains return,
without bringing the application to a stop or losing control
at any time. Several variants of kinetic back-up can be
selected.
Configure the behaviour of the frequency converter at
mains drop-out, in
parameter 14-10 Mains Failure and
parameter 1-73 Flying Start .
NOTICE
Coast is recommended for compressors as the inertia is
too small for flying start in most situations.
2.6.4 Built-in PID Controllers
The 4 built-in proportional, integral, derivative (PID)
controllers eliminate the need for auxiliary control devices.
One of the PID controllers maintains constant control of
closed-loop systems where regulated pressure, flow,
temperature, or other system requirements are maintained.
The frequency converter can provide self-reliant control of
the motor speed in response to feedback signals from
remote sensors. The frequency converter accommodates 2
feedback signals from 2 different devices. This feature
allows regulating a system with different feedback
requirements. The frequency converter makes control
decisions by comparing the 2 signals to optimise system
performance.
Use the 3 additional and independent controllers for
controlling other process equipment, such as chemical feed
pumps, valve control, or for aeration with different levels.
2.6.5 Automatic Restart
The frequency converter can be programmed to restart the
motor automatically after a minor trip, such as momentary
power loss or fluctuation. This feature eliminates the need
for manual resetting and enhances automated operation
for remotely controlled systems. The number of restart
attempts as well as the duration between attempts can be
limited.
2.6.6 Flying Start
Flying start allows the frequency converter to synchronise
with an operating motor rotating at up to full speed, in
either direction. This prevents trips due to overcurrent
draw. It minimises mechanical stress to the system since
the motor receives no abrupt change in speed when the
frequency converter starts.
2.6.7 Full Torque at Reduced Speed
The frequency converter follows a variable V/Hz curve to
provide full motor torque even at reduced speeds. Full
output torque can coincide with the maximum designed
operating speed of the motor. This differs from variable
torque frequency converters and constant torque
frequency converters. Variable torque frequency converters
provide reduced motor torque at low speed. Constant
torque frequency converters provide excess voltage, heat,
and motor noise at less than full speed.
2.6.8 Frequency Bypass
In some applications, the system may have operational
speeds that create a mechanical resonance. This can
generate excessive noise and possibly damage mechanical
components in the system. The frequency converter has 4
programmable bypass-frequency bandwidths. These allow
the motor to step over speeds that induce system
resonance.
2.6.9 Motor Preheat
To preheat a motor in a cold or damp environment, a small
amount of DC current can be trickled continuously into the
motor to protect it from condensation and cold starts. This
can eliminate the need for a space heater.
Product Overview
VLT
®
Refrigeration Drive FC 103
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