motortronics articles

Low and Medium Voltage Soft Starters for Compressor Applications

Motortronics

Soft Starters for Compressor ApplicationsLower Your Maintenance Cost and Reduce Mechanical Stress.

Piston Compressors
Screw Compressors
Centrifugal Compressors
Axial Compressors
Standalone Soft Starters or Packaged to Customer Specification

Built-in Functions:
Operator Interface
4 Ramp Control Choices
Dual Ramps
Jog Function
Kick Start Function
Pump-Flex Deceleration Ramp
Restart Delay Timer
Time Clock Controller
RS-485 Serial Communications

Low Voltage:
Power Components - 6 SCRs in inverse parallel pairs for full phase angle, soft start control (1600V PIV), RC snubber for dv/dt protection of each SCR pair
Line Voltage Range - 200 to 600 VAC, 3 phase +10% -15%, 50/60Hz
Current Ratings - 18 - 1250A depending on unit selection; range of each unit is 50-100% of max current rating
AC Supply Voltage - User supplied 120VAC +10% -15% tolerance, 60Hz; optional 240VAC 50Hz control available
Start/Stop Control Choices - 2-wire run-stop using dry contacts, 3-wire start/stop with built-in seal in contact, N.C. interlock input (dry contact) for remote devices

Medium Voltage:
Type of Load - 3-phase medium voltage AC induction or synchronous motors
AC Supply Voltage - 2300, 3300, 4160, 6000/7200V, 11-15kV, VAC +10% to -15%, 50/60 Hz line voltages
HP Ratings - Up to 10,000 HP @ 7.2kV (800 Amps), up to 20,000 HP @ 15kV (800 Amps); contact factory for higher rating requirements
Overload Rating - AC53b 600-30-60m
Power Circuits - Series strings of SCR power modules (1, 2 or 3 matched pairs of SCRs per phase depending on voltage rating)
BIL Rating - 2300V - 7200V 60kV, 11000 - 15000V (110kV)
Transient Voltage Protection - dv/dt circuits (1 per SCR pair)
Vacuum Bypass Contactor - Standard on all models, line start rated