VLT
®
6000 HVAC Series
Introduction to
HVAC
• Sleep mode, which automatically turns the
motor off, e.g. when there is no need for more
pressure or flow in a system.
• The "flying start" function enables the unit
to catch a rotating fan.
• Automatic ramp up/down to ensure that
the VLT 6000 HVAC will not trip during
acceleration or deceleration.
• All standard units have three integral, serial protocols
- RS 485 FC protocol, Johnson’s Metasys N2
and Landis/Staefa Apogee FLN. Communication
option cards that can be connected are LonWorks,
DeviceNet, Modbus RTU and Profibus.
■ Control principle
A frequency converter rectifies AC voltage from
mains into DC voltage, after which this DC
voltage is converted into a AC current with a
variable amplitude and frequency.
The motor is thus supplied with variable voltage and
frequency, which enables infinitely variable speed
control of three-phased, standard AC motors.
1. Mains voltage
3 x 200 - 240
VAC,50/60Hz.
3 x 380 - 460 V AC, 50 / 60 Hz.
3 x 525 - 600 V AC, 50 / 60 Hz.
2
. Rectifier
A three-pha
se rectifier bridge that rectifies AC
current into DC current.
3
. Intermediate circuit
DC voltage = 1.35 x mains voltage [V].
4
. Intermediate circuit coils
Even out t
he intermediate circuit voltage and reduce
the harmonic current feedback to the mains supply.
5
. Intermediate circuit capacitors
Even out the intermediate circuit voltage.
6
. Inverter
Converts DC voltage into variable AC voltage
withavariablefrequency.
7
. Motor voltage
Variable AC voltage, 0-100% of mains supply voltage.
8
. Control card
This is where to find the computer that controls
the inverter which generates the pulse pattern by
which the DC voltage is converted into variable
AC voltage with a variable frequency.
MG.61.A5.02 - VLT is a registered Danfoss trademark
9
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