INTRODUCTION
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the impedance of the human body , this circuit is called the Measuring Device (MD).
The instrument has five different MD circuits, selectable through the menu, which are
representative circuits designed to simulate the impedances of the human body under
different conditions. The impedance of the human body will vary depending upon point
of contact, the surface area of the contact and the path the current flows. For these
reasons the specifications on the Measuring Devices differ depending upon the type of
test being performed as well as the maximum allowable leakage current. Leakage current
measurements are performed on products under both normal conditions and single fault
conditions as well as reversed polarity. This simulates possible problems which could
occur if the product under test is faulted or misused while the product is operating under
high line conditions (110% of the highest input voltage rating of the product).
Line Leakage tests are normally specified as “Type Tests” or “Design Tests” which are
performed during the development of the product. This helps verify that the design is safe
but it does not guarantee the safety of the products being produced on the production line.
The only way to be sure you are shipping safe products is to test each product at the end
of the production line. The built in switching matrix interface allows the 7611 to be
interconnected with other AR safety testers to form a complete safety testing system.
The user may perform a Leakage Current test along with other common safety test such
as Dielectric Withstand, Insulation Resistance, and Ground Bond on the production line
with a single connection to the device under test.
1.4 The Dielectric Withstand (Hipot) Test
The principle behind a dielectric voltage - withstand test is simple. If a product will
function when exposed to extremely adverse conditions, it can be assumed that the
product will function in normal operating circumstances.
The most common applications of the dielectric-withstand test are:
•
Design (performance) Testing.... determining design adequacy to meet service
conditions.
•
Production Line Testing.... detecting defects in material or workmanship during
processing.
•
Acceptance Testing.... proving minimum insulation requirements of purchased parts.
•
Repair Service Testing.... determine reliability and safety of equipment repairs.
The specific technique varies with each product, but basically, during a dielectric voltage
- withstand test, an electrical devise is exposed to a voltage significantly higher than it
normally encounters. The high voltage is continued for a given period of time.
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