For a project I'm doing, I need a key with three positions. However, in order to avoid overvoltages, it can not be open when switching from one pole to another. For example, to switch from pole 1 to pole 2, it must first connect to 2 without leaving 1 and then disconnect from 1 only 2.

Does anyone know the name of this type of key? I've read something about it in a book, but I have no details about it.

 

That type of operation is normally called "shorting" or "make-before-break." I have no idea if it is something that is easy to find in a key-operated switch. It is reasonably common for conventional rotary switches. Some manufactures will offer a particular model of switch with either that operation mode or "non-shorting"/"break-before-make" but for many only the non-shorting type is available.

 

I have used Grayhill in the past, they make all kinds of rotary switches, break before make, or make before break.
Max.

 

That type of operation is normally called "shorting" or "make-before-break." I have no idea if it is something that is easy to find in a key-operated switch. It is reasonably common for conventional rotary switches. Some manufactures will offer a particular model of switch with either that operation mode or "non-shorting"/"break-before-make" but for many only the non-shorting type is available.

I'm just thinking of using a rotary switch.

 

Not all rotors switches will make-before-break. Here is one.

https://www.digikey.com/products/en...ty=0&ColumnSort=0&page=1&stock=1&pageSize=250

 

For a project I'm doing, I need a key with three positions. However, in order to avoid overvoltages, it can not be open when switching from one pole to another. For example, to switch from pole 1 to pole 2, it must first connect to 2 without leaving 1 and then disconnect from 1 only 2.

Does anyone know the name of this type of key? I've read something about it in a book, but I have no details about it.

As mentioned what you want is commonly called a make before break type switch which come in several flavors with rotary type likely the most common and popular. You may wish to look at the Grayhill 5000 Series. Like Max I used Grayhill in many of my designs. There are dozens of other manufacturers as well.

What you don't mention is the switching current and voltage? In a design world switches become a small world unto themselves. Load current aside things like switching current, switching voltage and a host of other mechanical and electrical specifications come into play.

Ron

 

What is the source of these overvoltages? Can you share a circuit? I think suppressing overvoltages is far easier than finding exotic switches.