New Industry Products

Cornell Dubilier Unveils New Series of AC Filter Capacitors Aimed at Harsh Environments

April 08, 2021 by Gary Elinoff

The new capacitors are 85/85 temperature humidity at bias (THB) qualified

Cornell Dubilier’s (CDE) ALH series of AC-rated filter capacitors successfully endure 1,500 of grueling THB testing, while competitive units were validated for only 1,000 hours, representing an advantage of 50%


Members of the ALH series of AC-rated filter capacitors. Image courtesy of CDE
Members of the ALH series of AC-rated filter capacitors. Image courtesy of CDE

ALH series was subjected to the demanding TBD test. Here, the units must carry their rated voltages at 85°C and at 85% relative humidity, conditions mimicking what the devices may encounter in harsh automotive, industrial and commercial environments. Thus qualified, these AC filter capacitors can endure where lesser devices might fail. 

Of course, series members last a lot longer in “gentler” environments. CDE mentions a life expectancy of “100,000h @ 70 °C hot spot, rated voltage” 


Optimized for AC Harmonic Filtering 

Members of the series are optimized for AC harmonic filtering on both the input and output of inverter circuits. They feature high rms current ratings in order to handle higher-ordered harmonics.    


Large Numbers of Choices

The ALH series features voltage ratings of 160, 250, 275, 350, 400 and 450 VAC, with multiple availabilities in each of the rated voltage strata. Available capacitances range from 0.22 to 50 microfarads. 

In the 160 volt group, for example, capacitances range from 1.0 to 50µF, while members of the 450 volt group sport a range of 0.22 to 10.0µF. CDE provides a complete listing of specifications for each capacitor in the series datasheet.



As per the THB test, series members can operate at rated voltage for 1500 hours at 85℃ and 85% humidity. The complete operating range for the devices is  -40 to 105 °C. However, at temperatures greater than 85 ºC, the rated voltage must be derated by 1.35% per degree centigrade.



  • Test voltage between the terminals: 150% of equivalent DC voltage for 10 seconds (equivalent DC voltage is 1.414 of the VAC)
  • Test voltage between the terminals and the case: @50/60 HZ, 3 kVac for 10 seconds
  • Insulation resistance is greater than 30,000 MΩxµF (the product of resistance times capacitance) at 100 VDC and 25℃ after one minute


Other Highlights

Standard capacitance tolerances for the ALH series are plus or minus 10%. The units can optionally be specified for plus or minus 5%.

The capacitors have been specifically aimed at the demanding automotive environment, and have been designed to stand up to the tough electrical and mechanical testing required in that arena. For increased reliability, the units are self healing.

Member of the series are suitable for high frequency applications.



These tough devices will find application in in the harshest environments, including:

  • Solar and EV inverters
  • Motor drives
  • Traction
  • UPS
  • Portable power systems
  • AC-tuned harmonic reduction filters




Case sizes vary from 32 x 20 x 11 mm to 57.5 x 50 x 35 mm 

Two or four leads

Plastic case and dry resin both meet UL94V-0 


Regulatory and Safety


  • UL listed
  • IEC 61071
  • AEC-Q200 qualified