Teledyne 701 Manuel D’Utilisation

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Teledyne API Model 701 Zero Air Generator 
A Primer on Electro-Static Discharge 
01671H (DCN6051) 
8-3 
Potentially damaging electro-static discharges can occur:  
 Any time a charged surface (including the human body) discharges to a device.  Even 
simple contact of a finger to the leads of a sensitive device or assembly can allow enough 
discharge to cause damage.  A similar discharge can occur from a charged conductive 
object, such as a metallic tool or fixture. 
 When static charges accumulated on a sensitive device discharges from the device to 
another surface such as packaging materials, work surfaces, machine surfaces or other 
device.  In some cases, charged device discharges can be the most destructive. 
 
A typical example of this is the simple act of installing an electronic assembly into the 
connector or wiring harness of the equipment in which it is to function.  If the assembly 
is carrying a static charge, as it is connected to ground a discharge will occur. 
 Whenever a sensitive device is moved into the field of an existing electro-static field, a 
charge may be induced on the device in effect discharging the field onto the device.  If the 
device is then momentarily grounded while within the electrostatic field or removed from 
the region of the electrostatic field and grounded somewhere else, a second discharge will 
occur as the charge is transferred from the device to ground. 
8.3 Common Myths About ESD Damage 
 I didn’t feel a shock so there was no electro-static discharge: The human nervous 
system isn’t able to feel a static discharge of less than 3500 volts.  Most devices are 
damaged by discharge levels much lower than that. 
 I didn’t touch it so there was no electro-static discharge:  Electro-static charges are 
fields whose lines of force can extend several inches or sometimes even feet away from 
the surface bearing the charge. 
 It still works so there was no damage: Sometimes the damaged caused by electro-
static discharge can completely sever a circuit trace causing the device to fail 
immediately.  More likely, the trace will be only partially occluded by the damage causing 
degraded performance of the device or worse, weakening the trace.  This weakened 
circuit may seem to function fine for a short time, but even the very low voltage and 
current levels of the device’s normal operating levels will eat away at the defect over time 
causing the device to fail well before its designed lifetime is reached. 
These latent failures are often the most costly since the failure of the equipment in 
which the damaged device is installed causes down time, lost data, lost productivity, as 
well as possible failure and damage to other pieces of equipment or property. 
 Static Charges can’t build up on a conductive surface:  There are two errors in this 
statement. 
Conductive devices can build static charges if they are not grounded.  The charge will 
be equalized across the entire device, but without access to earth ground, they are still 
trapped and can still build to high enough levels to cause damage when they are 
discharged.