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
  • FANDSTEEL
  • 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 !

SELENIUM POWER RECTIFIERS

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.

SELENIUM SUPPRESSORS

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

Construction

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.

Efficiency

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

Heat pipes coolers are like the Loch Ness monster... lot's of people are speaking about, but few people have really tested them! This technology sounds a little bit mysterious for people coming from a pure electronics background ! How can such a thing (looking like a basic copper tube), would be able to convey something like 1000 time more calories than the best typical thermal conductor in electronics : copper ! You will certainly find the answer in our dedicated page to the heat pipe functioning, or to heat pipe page on wikipedia, if you want to go deeper in the subject. [caption id="attachment_1877" align="aligncenter" width="685"]Heat Pipe functionning Heat Pipe functionning[/caption]

Thermal management challenges in power electronics

As it was explained in our market analysis article about SIC semiconductors, power electronics is currently at the beginning of a revolution. Semiconductors are now able to work up to incredibly high frequency (50 to 100kHz), with excellent efficiency, and low losses. Because working at high frequency leads to reducing size and weight, this revolution increasesthe density of power losses. New thermal management challenges are in front of us. But good news, heat pipes are here to help solving them ! Here are the main reasons why ?

Heat pipe advantages

  • High thermal conductivity. Because heat pipes are using one of the most efficient way to convey calories : phase change, their high thermal conductivity will be the best advantage to solve your thermal management issues.
[caption id="attachment_1880" align="aligncenter" width="300"]Heat Pipe thermal conductivity simulation Heat Pipe thermal conductivity simulation[/caption]
  • Temperature range. It is mainly depending from the working fluid inside the heat pipe. Considering most of the power electronics application going from 50 to 200 degC, you will not find a better fluid than water. Good news, water is not dangerous and not explosive as you may know... Bad news, water is electrically conductor as you may know too. Electronics designer never sleeps soundly when water flows close to their components ! If you feel a bit of apprehension, read our next point.
 
  • Reliability. Heat pipes are excellent in reliability because they use no mooving mechanical parts and need no energy like electricity. No worry about maintaining the motor or the filter of your pump like in a cooling loop. The difference of temperature is the only "motor" which garanty an endless  functionning. Heat pipes are commonly used in aerospace application and railway, where life cycle of the product can be up to 50 years !
[caption id="attachment_1861" align="aligncenter" width="300"]Railway Heat Pipe Cooler Railway Heat Pipe Cooler[/caption] We hope this article have contributed to better understanding of heat pipes.

Contact us

For any question, enquiry, contact COUGAR ELECTRONICS here. Our thermal engineers will be happy to help :-)
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