Re: ground straps

Subject: Re: ground straps
From: "Wollt, Richard C RV" <rcw1 -at- PO9 -dot- RV -dot- UNISYS -dot- COM>
Date: Thu, 28 Sep 1995 14:57:00 CDT


I'm one of the engineers who fell into writing, but i've had 13 years of
experience chasing and solving mainframe system environmental problems,
including electrostatic discharge (ESD) caused problems. I expect you will
find a definite geographical correlation, and probably a seasonal one as

Static is generated when materials separate; for example when you pull tape
off of a roll, or when you roll your chair across the carpet. How much
charge can accumulate depends on the conductivity of the materials involved,
including the condictivity of the air surrounding the charged object. As
the relative humidity increases, the conductivity of air increases rapidly.
Above 50 % RH, it is very difficult to generate and maintain enough voltage
to disrupt a system or a PC. You can easily damage a chip or transistor
that is not in the socket.

At low humidities, like in Arizona, a person can generate and carry several
thousand volts and thus can easily cause disruption to a system.

Note: some transistors can be destroyed by 40 volts of ESD. A person does
not sense the discharge (feel a shock) until the ESD discharge exceeds about
2400 volts.

Richard Wollt

Previous by Author: Re: Archiving outdated documentation
Next by Author: Re: Re[2]: bogus resume stuff
Previous by Thread: ground straps
Next by Thread: simplicity

What this post helpful? Share it with friends and colleagues:

Sponsored Ads