Danfoss VLT HVAC Design Guide

2.8 Control Structures
2.8.1 Control Principle
Illustration 2.8: Control structures.
The frequency converter is a high performance unit for demanding applications. It can handle various kinds of motor control principles such as U/f special
motor mode and VVC plus and can handle normal squirrel cage asynchronous motors.
Short circuit behavior on this FC depends on the 3 current transducers in the motor phases.
In par. 1-00
Configuration Mode it can be selected if open or closed loop
is to be used
2.8.2 Control Structure Open Loop
Illustration 2.9: Open Loop structure.
In the configuration shown in the illustration above, par. 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 Introduction to VLT HVAC Drive VLT
®
HVAC Drive Design Guide
32 MG.11.B9.02 - VLT
®
is a registered Danfoss trademark
2

Danfoss VLT HVAC Specifications

General

Enclosure Rating	IP20, IP21, IP54, IP55, IP66
Storage Temperature Range	-25°C to +70°C
Output Voltage Range	0-100% of supply voltage
Communication Protocols	Modbus RTU, BACnet, Ethernet/IP, Profibus DP
Ambient Temperature Range	-10°C to +50°C (without derating)
Relative Humidity	5% to 95% non-condensing
Altitude	Up to 1000 m without derating
Cooling Method	Air cooled
Application	HVAC systems, Pumps, Fans, Compressors
Voltage Range	200-240 V, 380-500 V, 525-600 V
Frequency Range	0 Hz to 590 Hz