| Q. |
What is a Line Leakage test? |
| A. |
A Line Leakage test is a term used to describe a series of tests that monitor
the leakage current produced by a product while it is operating. The input voltage
to the product is normally adjusted for its highest rated mains voltage, or a value
that is 110% of the highest rated mains voltage. A Line Leakage test can include any
or all of the following: Earth Leakage test, Enclosure Leakage test, and Applied Part
test. The leakage current levels are monitored through a measuring device (MD) which
simulates the impedance of the human body. The tests conducted on the products are
performed during both normal and single fault conditions.
|
| Q. |
What products require a Line Leakage test? |
| A. |
Generally, Line Leakage tests are most often performed on medical products,
as the standards for leakage current are much stricter than for consumer products.
In the past, Line Leakage tests were normally specified as type tests but are now
being performed more frequently as production line tests. Contact your local safety
agency office or our Technical Services department for more information.
|
| Q. |
What is the difference between a Line Leakage test and a Hipot test |
| A. |
There are a number of differences between these two tests but in general the
differences can be summarized as follows: A Hipot test uses a high voltage to stress
the insulation of a product in order to determine if the insulation can adequately
prevent leakage current flow. A Line Leakage test measures the effects of a product’s
leakage current flow during normal and single fault conditions while the product is
operating.
|
| Q. |
Is there any correlation between Hipot leakage current and leakage from a Line Leakage test? |
| A. |
Yes. The current measured during an open neutral Earth or Enclosure Leakage test
can be used to approximate the current trip setting that should be used for a Hipot test.
The following formula may be used: (Hipot test voltage / Line Leakage test voltage) *
Line Leakage reading = Approx. Hipot current.
|
| Q. |
What is an acceptable level of leakage current during a Line Leakage test? |
| A. |
There are very specific agency guidelines on acceptable levels of leakage current.
They can very from 0.01 - 5 mA depending on the test being performed. Check safety
agency guidelines for your specific product to be sure.
|
| Q. |
What is an Earth Leakage test? |
| A. |
The Earth Leakage test measures the leakage current in the ground conductor back to
the system neutral of a Class I product. The test is performed with every possible
combination of open and closed earth conductors, normal and reversed polarity conditions,
and with the neutral conductor open and closed. The measurements are done through a
measuring device (MD) which simulates the impedance of the human body.
|
| Q. |
What is an Enclosure Leakage test? |
| A. |
The Enclosure Leakage test measures the continuous leakage current from the enclosure
back to the system neutral of Class I and Class II products. On Class I products the
test is performed with every combination of open and closed earth conductors, normal
and reversed polarity conditions, and with the neutral conductor open and closed. On
Class II products a 10 x 20 cm foil is attached to the enclosure and the leakage is
measured from the foil to the system neutral under normal and reversed polarity conditions
with the neutral conductor open and closed. The foil applied to the enclosure simulates
a surface contact with the enclosure approximately the size of the hand.
|
| Q. |
What is a Patient/Applied Part Leakage test? |
| A. |
The Patient Applied Part Leakage test measures the continuous leakage current
flowing from an applied part via the patient to the system line or neutral or from
the patient via an F-type applied part to the system line or neutral.
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