Danfoss vlt aqua Design Guide

2.8.3 Local (Hand On) and Remote (Auto On) Control
The adjustable frequency drive can be operated manually via the local control panel (LCP) or remotely via analog/digital inputs or serial bus.
If allowed in par. 0-40
[Hand on] Key on LCP , par. 0-41 [Off] Key on LCP , par. 0-42 [Auto on] Key on LCP , and par. 0-43 [Reset] Key on LCP , it is possible
to start and stop the adjustable frequency drive byLCP using the [Hand ON] and [Off] keys. Alarms can be reset via the [RESET] key. After pressing the
[Hand On] key, the adjustable frequency drive goes into hand mode and follows (as default) the local reference set by using the LCP arrow keys up
[▲] and down [▼].
After pressing the [Auto On] key, the adjustable frequency drive goes into
auto mode and follows (as default) the remote reference. In this mode,
it is possible to control the adjustable frequency drive via the digital inputs
and various serial interfaces (RS-485, USB, or an optional serial commu-
nication bus). See more about starting, stopping, changing ramps and
parameter set-ups, etc. in par. group 5-1* (digital inputs) or par. group
8-5* (serial communication).
130BP046.1
0
Hand Off
Auto
LCP Keys
Reference Site
par. 3-13
Reference Site
Active Reference
Hand Linked to Hand / Auto Local
Hand -> Off Linked to Hand / Auto Local
Auto Linked to Hand / Auto Remote
Auto -> Off Linked to Hand / Auto Remote
All keys Local Local
All keys Remote Remote
The table shows under which conditions either the Local Reference or the Remote Reference is active. One of them is always active, but both can not be
active at the same time.
NOTE!
Local Reference will be restored at power-down.
par. 1-00 Configuration Mode determines what kind of application control principle (i.e., open-loop or closed-loop) is used when the Remote Reference
is active (see table above for the conditions).
2.8.4 Control Structure Closed-loop
The closed-loop controller allows the drive to become an integral part of the controlled system. The drive receives a feedback signal from a sensor in the
system. It then compares this feedback to a setpoint reference value and determines the error, if any, between these two signals. It then adjusts the
speed of the motor to correct this error.
For example, consider a pump application where the speed of a pump is to be controlled so that the static pressure in a pipe is constant. The desired
static pressure value is supplied to the drive as the setpoint reference. A static pressure sensor measures the actual static pressure in the pipe and supplies
this to the drive as a feedback signal. If the feedback signal is greater than the setpoint reference, the drive will slow down to reduce the pressure. In a
similar way, if the pipe pressure is lower than the setpoint reference, the drive will automatically speed up to increase the pressure provided by the pump.
2 Introduction to the VLT AQUA Drive VLT
®
AQUA Drive Design Guide
2-12 MG.20.N5.22 - VLT
®
is a registered Danfoss trademark
2

Danfoss vlt aqua Specifications

General

Supply Voltage	200-240V, 380-500V, 525-600V
Enclosure	IP20
Features	Energy optimization
Approvals	CE, UL, cUL
Input Voltage Range	200-240V, 380-500V, 525-600V
Output Voltage Range	0 to supply voltage
Protection Features	Overvoltage, Undervoltage, Overcurrent, Short circuit, Ground fault
Communication Interfaces	PROFIBUS
Cooling Method	Air-cooled