Cirris Signature 1000HN, Руководство пользователя

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Section 10: Select a Test Procedure / Tips on selecting Hipot Voltage settings
1000HN User’s Guide / page 46
Tips on selecting
Hipot Voltage settings
Remember, when you select a hipot voltage, you are setting the amount of voltage to
be applied between pins that are not connected. Remember these things when you
select hipot voltage settings:
• The more voltage you use, the more likely the analyzer is to detect
contamination between pins, or frayed wires that almost create a short
circuit. However, higher test voltages only work well on cables with
little pin-to-pin capacitance.
• Higher voltage settings require greater pin-to-pin spacing on cable
connectors.
• Subjecting a cable assembly to excessive voltage may degrade its future
performance. Use the lowest voltage setting that still finds insulation
problems in a cable. Most cables require no more than 630 volts. Most
ribbon cables are designed to handle a maximum of about 300 volts.
• The hipot test applies high voltage to a net (a group of connected pins)
and measures the current that flows from the net. The analyzer does not
determine which net or pin the current is flowing to. This means that if
several nets have leakage, you cannot tell which nets leak to each other.
Hipot voltage and
capacitance problems
Excessive capacitance in a cable assembly is a major consideration when you are
deciding on what Hipot Voltage, Hipot Duration, and Insulation Resistance settings to
use. If a cable has shielding or a grounded net, capacitance problems are more likely
to occur. Remember these things:
• In general, the higher the capacitance a cable has, the lower a hipot volt-
age setting you’ll be able to use. See page 20 for further information.
• If you find that a cable has excessive capacitance, first try lowering the
Hipot Voltage
setting. You may also set the
Single Net Error
option to
Is Ignored
. This will cause the analyzer to ignore a single-net hipot fail-
ure. (A single-net hipot failure is an indication of the presence of a net
with high capacitance, a net with too many points, or a net that tests as
borderline.) Normally, hipot failures show up with at least two failed
nets.
• If you’ve set the
Apply Hipot
option to
Connections Only
, the analyzer
will not detect leakage of a single net to any unconnected pins.
Tips on selecting
Insulation Resistance
settings
Remember, when you select an Insulation Resistance setting, you are specifying the
lowest resistance that should appear between unconnected points. See page 20 for
more information on Insulation Resistance versus Hipot Voltage settings. Remember
these things:
• Using the highest setting might increase your chances of finding some
kinds of errors. You might not want to use an extremely high setting.
Oil, solder flux, or fingerprints left over from the manufacturing process
can become conductive in high relative humidity conditions.