Emergency cut-off switch - it’s probably an electrical contact

Chances are, if you’ve worked on or around an assembly line, or operated industrial machinery, you’re familiar with an emergency stop button.  Even if you haven’t worked in a factory setting the concept is commonly understood.  In an emergency, press the big red stop button or pull the chain, etc.

But what exactly does an emergency stop button do?

The exact methodology of an emergency stop button varies.  In large complex assembly lines, running at high speeds, it can be dangerous to apply instant braking to the entire line.  Items on the line could be thrown off or swing about, potentially causing harm to people and property.  Generally, where humans are working, equipment will be stopped quickly, since it’s likely the emergency involves a worker in peril.  But even in systems where sudden stops aren’t possible one of the first things that happens when an emergency stop button is pushed, is the power is cut off.

Emergency cut-offs use electrical contacts

There are different ways an emergency stop button can operate a contact.  The stop button itself might be a simple normally closed contact that when pressed is opened, hence breaking the circuit and cutting power.  Or the button will trigger contacts to “engage” a braking system.  Of course in reality, in an industrial environment, it’s probably a combination of the two, along with other safety mechanisms that swing into action.

Electrical contacts are everywhere

It's difficult to deal with anything electrical without encountering electrical contacts.  Something as common and mundane as a light switch uses contacts.  The usage, however, most commonly associated with electrical contacts is magnetic motor control.  Contacts open and close to permit or interrupt the flow of electrical power to a motor.  Marlton NJ based Repco Inc. manufacturers quality, lower-cost replacement electrical contacts for 25 industrial control manufacturers.