Selenium Rectifier & Supressor

Cougar Electronic is producing standard and custom design selenium rectifier & Selenium Supressor. Still commonly used in industrial application, do not hesitate to send your design for any quotation.

All our selenium rectifiers and suppressors are made in house. That allows us :

  • to be price competitive
  • provide fast delivery
  • manage quality and customer satisfaction

Selenium components are very interesting for their reliability. Those components have the ability to recover after surge failure, which make them excellent for security applications.

COUGAR ELECTRONICS can supply OEM replacement parts for the following list of manufacturers and suppliers :

  • AEG Telefunken
  • Bradley Labs
  • CKE
  • EDAL
  • FMC
  • General Electric
  • International Rectifier
  • IRC
  • ITT
  • PD&E
  • Radio Receptor Corp
  • Rectico
  • Sarkes Tarzian
  • Semikron
  • Siemens
  • ST Semicon
  • Syntron
  • Tung Sol
  • Vickers
  • Westcode
  • Westinghouse
Get a quote !


A selenium rectifier is an electronic component that permits free passage of electric current in one direction, but almost completely blocks the flow of current in the opposite direction. Like a silicon diode, when an alternating current is applied to a selenium rectifier in series with the load, half of the AC cycle is blocked and the load receives a pulsating direct current. by using two or more rectifiers in an appropriate center tap or bridge circuit, both halves of the AC cycle may be rectified !

Main parameters :

  • Voltages: Standard Voltages per cell up to 36 v rms. The voltage rating is determined by the number of cells in series
  • Current: Ratings are determined by the size of the cell, the number of cells in parallel, the circuit configuration and the type of cooling, Current Ratings of 0.5 amps for a 1.0 X 1.0 cell in a half wave configuration to 270 amps for a 8.0 X 16.0 cell in a 6 phase circuit.
  • Circuits:Half wave, Doublers. Center Taps, Full Wave Bridges single and three phase.


Selenum surge suppressors are designed to protect semiconductors from damage due to transient surges.

The selenium suppressors are used in applications to protect other components in the circuit such as motor- generators and other circuits with inductive components.

Main parameters :

  • Ratings: Determined by the cell size and number of cells in a series similar to the power rectifiers.
  • Suppressors are also rated by the voltage clamping factor and the amount of reverse energy in joules that they can absorb.

If you have any question, don't hesitate to contact us:

Cougar Electronics Corp. | 10 Lyman Street, New Haven, CT 06511 | Phone: (203) 562-6545 Fax: (203) 562-6748

More about the Selenium technology


The basis of the selenium rectifier is the cell. An Aluminum back plate is treated to provide a tight, low resistance contact with the layer of specially prepared selenium which is next applied. After the selenium coating is cured by a thermo-chemical process, a special counter-electrode alloy is applied to the selenium face.

these operations are conducted in air-conditioned and dust-free surroundings under conditions of cleanliness and chemical purity.

After these operations have been accomplished, the cells are subjected to a treatment which consists of impressing a controlled voltage in the reverse or blocking direction. This electro-forming operation creates a barrier layer of rectifying junction between the selenium and the counter-electrode. This is at this point that rectification takes place.

A selenium rectifier may be a single cell or an assembly of cells in various circuit connections. In a multiple cell rectifier, cells are assembled on an insulated center bolt stud with spacing washers and contractors interposed between the cells. The separation allows free passage of air for natural or forced convection cooling.

Cells are insulated from the center bolt or stud by means of insulating tubing. The AC and DC terminals are assembled over the mounting stud in whatever arrangement is necessary for the type connection desired and cross connections can be made between terminals to connect portions of the rectifier as necessary.


The conversion efficiency of typical selenium rectifier is approximately from 70% to 91%. The largest percentage of the losses in the rectifier are a function of current and the forward resistance. Best efficiency is therefore obtained by operating the rectifier at the nominal RMS voltage rating.

Selenium Rectifier & Suppressor

There has been a notable increase in the developpment of Silicon Carbide semiconductor materials (SiC) in the past few years. It seems we are now close to a massive use of those new solutions, made possible by the considerable number of peoples working on the subject and price drop down. The adoption of SiC solutions are mainly driven by two factors : the miniaturization and the efficiency. Silicon Carbide based devices are a very promising answer to the market pressure on power converters compactness and efficiency. The lower maximum junction temperature, allow higher density of power on the semiconductors, wich leads to decrease the size of the cooling components. Nevertheless, this positive effect is also making the thermal management challenge harder. Water cooled and heat pipes solutions are now commonly considered by power electronics engineers see cougar electronics solutions for thermal management [caption id="attachment_2308" align="aligncenter" width="300"]Silicon Carbide Silicon Carbide Losses[/caption] SiC are also well known for their capacity to work at higher frequency than classical silicon based MOSFETs and IGBTs. The magnetics components size like inductors, and transformers is mainly linked to the frequency. In this way, increasing the frequency of the device drastically allow to reduce the size and thus the weight of the magnetics components. SiC technology has been massively adopted by early adopter applications like Solar Inverter and UPS. The adoption of this new technology is slower in the high power industry like motor drives, tractions and electrical grid converters due to the reluctance in the use of new material. The market of high power Silicon Carbide semiconductors is mainly holded by niche players, that were pioneers in their field. Most of the big semiconductor manufacturers are releasing or close to release new range of devices that will trigger the signal of a massive adoption. Contact COUGAR ELECTRONICS for advises and availablity of your semi-conductor. Other links : IEEE article about SiC