Danfoss VLT Pocket Guide

32 VLT
®
Soft Starter Pocket Guide
Soft starters are more fl exible and reliable than primary resistance
starters.
Primary resistance starters cannot accommodate varying load
conditions (e.g. loaded or unloaded starts) and the start torque cannot
be fi ne-tuned to match motor and load characteristics. Performance
may vary with multiple starts in close succession, because the start
profi le changes as the resistance heats up. Damaging torque and
current transients still occur at the steps between voltages, and
primary resistance starters are not capable of providing soft stop.
Primary resistance starters are large and expensive, and liquid
resistance starters require frequent maintenance.
Primary Resistance Starters: How does soft start
compare to primary resistance starting?

Danfoss VLT Specifications

General

Frequency	50/60 Hz
Enclosure	IP20, IP21, IP55, IP66
Series	VLT
Control Technique	Flux Vector Control
Output Voltage	0-Vinput
Control Method	Fieldbus
Communication Interface	PROFIBUS, CANopen
Protection Features	Overload, Overvoltage, Undervoltage, Short Circuit, Ground Fault
Cooling Method	Liquid Cooled
Storage Temperature	-25°C to +70°C
Relative Humidity	5-95% non-condensing
Altitude	Up to 1000m (3280ft) without derating, up to 4000m (13120ft) with derating
Operating Temperature	-10°C to +50°C (14°F to 122°F)