Control Structures - Danfoss VLT HVAC Basic Drive FC 100 Series Design Manual

Introduction to VLT HVAC Ba...

2.6 Control Structures

In 1-00 Configuration Mode it can be selected if open or closed loop is to be used.
2.6.1 Control Structure Open Loop
Reference
handling
Remote
reference
Auto mode
Hand mode
Local
reference
scaled to
Hz
LCP Hand on,
off and auto
on keys
Illustration 2.7 Open Loop Structure
In the configuration shown in Illustration 2.7, 1-00 Configuration Mode is set to Open loop [0]. The resulting reference from
the reference handling system or the local reference is received and fed through the ramp limitation and speed limitation
before being sent to the motor control.
The output from the motor control is then limited by the maximum frequency limit.
2.6.2 Local (Hand On) and Remote (Auto On) Control
The frequency converter can be operated manually via the local control panel (LCP) or remotely via analog/digital inputs or
serial bus.
If allowed in 0-40 [Hand on] Key on LCP, 0-44 [Off / Reset] Key on LCP, and 0-42 [Auto on] Key on LCP, it is possible to start and
stop the frequency converter by LCP using the [Hand On] and [Off/Reset] keys. Alarms can be reset via the [Off/Reset] key.
After pressing the [Hand On] key, the frequency converter goes into Hand Mode and follows (as default) the Local reference
set by using the LCP arrow keys up [
After pressing the [Auto On] key, the frequency converter goes into Auto mode and follows (as default) the Remote
reference. In this mode, it is possible to control the frequency converter via the digital inputs and RS-485. See more about
starting, stopping, changing ramps and parameter set-ups etc. in parameter group 5-1* (digital inputs) or parameter group
8-5* (serial communication).
Hand Off
On Reset
Local reference will force the configuration mode to open loop, independent on the setting of 1-00 Configuration Mode.
Local Reference will be restored at power-down.
VLT HVAC Basic Drive Design Guide
P 4-14
Motor speed
high limit [Hz]
Remote
Reference
Local
P 4-12
Motor speed
low limit [Hz]
▲ ▼
] and down [ ].
Auto
On
®
MG.18.C2.02 - VLT is a registered Danfoss trademark
100%
P 3-4* Ramp 1
P 3-5* Ramp 2
0%
Ramp
100%
-100%
2
To motor
control
P 4-10
Motor speed
direction
23
2