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Variable frequency drives

CPX 18-pulse variable frequency drives

Demand more clean power.

The CPX series of variable frequency drives uses advanced 18-pulse clean power technology that significantly reduces line harmonics at the drive input terminals—resulting in one of the purest sinusoidal waveforms available. They prevent upstream transformer overheating and overloading, enabling the application of generators and other high-impedance systems.

Core features of the CPX 18-pulse VFD

  • Clean power: This cost-effective solution provides reductions in voltage and current harmonics.
  • Reliability: This VFD provides increased input protection for the adjustable frequency drive and its semiconductors from line transients.
  • Communications options: A wide range of communication protocols includes DeviceNet, PROFIBUS, Modbus RTU and Modbus TCP.

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Specifications

Eaton's enclosed drives portfolio

Standard options

Enclosure options

  • NEMA Type 1, 1 filtered,12, 3R, 7
  • Wall-mount
  • Floor-mount
  • Space heater

Pilot device options

  • Indicating lights
  • Pushbuttons
  • HOA switches
  • Speed potentiometers
  • E-stops
  • External keypad

Control options

  • CPT
  • Terminal blocks
  • Control relays
  • Timers

Metering options

  • Elapsed time meter
  • Volt meter
  • Amp meter
  • Frequency meter
  • Power meter

Input power options

  • Circuit breaker disconnect
  • Fused disconnect
  • Fuses
  • Surge protection
  • Input reactor

Bypass options

  • Three-contactor bypass
  • Reduced voltage soft starter (RVSS) bypass

Output power options

  • Output contactor
  • Output reactor
  • dV/dt filter
  • Sine wave filter

Technology comparison

Technology
Eaton VFD type
How it works
Typical THD
Advantages
Disadvantages
Inductive reactors

EGS

SVX

Mitigates higher-order harmonics by providing high input impedance that limits high-frequency currents. 33-38%
Low-cost, simple application

Low effectiveness

Voltage drop concerns

12-Pulse converters
HCX
Two parallel 6-pulse converters fed by parallel isolation transformer paths, phase shifted 30°, which mitigates 5th and 7th order harmonics. Input impedance mitigates higher-order harmonics as well. 12-18%

Simple to apply

Extremely robust

Not as effective as other methods

Relative high cost compared to passive filter

Passive filters

EGF

CFX

Provides high input impedance for higher-order harmonics and a shunt-tuned reactor and capacitor to mitigate 5th and 7th harmonics. 6-8%

Simple retrofit

Low cost for performance

Insensitive to voltage balance

Challenges with generator design

Power factor issues

Less robust than 18-pulse

18-Pulse converters
CPX
Three parallel 6-pulse converters fed by a single-phase shifting autotransformer, phase shifted 20° to cancel all harmonics below the 17th. Input impedance mitigates higher-order harmonics as well. 3-6%

Simple to apply

Extremely robust

Higher cost on small hp
Active Front End drives
RGX
IGBT-based front end pulls relatively linear power from the line and uses a L-C-L filter to mitigate the IGBT switching noise. 3-5%

Slightly higher efficiency

Immune to voltage imbalance

Regeneration capability

High cost, not as robust as 18-pulse
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