Chroma 19032-P, Быстрый старт

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Electrical Safety Analyzer 19032-P Quick Start Guide
4.4.3 OFFSET
1. DC OFFSET: Before testing WDC mode, please connects test cable
first. After the fixture is tested, then processes OFFSET for ensure
test value accuracy. The current calculation formula: Current reading
= Current real measurement value – Offset value.
2. AC OFFSET: Before testing WAC mode, please connects test cable
firstly. After the fixture is tested, then processes OFFSET for ensure
test value accuracy. Especially when test voltage is higher and
leakage current of test fixture and instrument is more increase. The
happened of Offset current is often caused by capacitance feature.
According to mathematics, when test a resistive load, its’ current value
=
2 2
( ) Offset
. Therefore, when measured
out resistive load current value, current reading =
(Resistance load value)
+
2 2
( ) Offset
−
. When tests a capacitive load, current
reading = (real measurement value) – (Offset).
(Real measurement value)
3. LC OFFSET: Before testing dynamic leakage current mode, please
connects test cable first. After the fixture is tested, then processes
OFFSET for ensure test value accuracy especially when measures
small current. The leakage current of general test fixture, isolation
transformer and the instrument are mostly caused by capacitance
feature. According to mathematics, when test a resistive load, its
current value =
2 2
( ) Offset
. Therefore,
when measured out resistive load current value, current reading =
(Resistance load value)
+
2 2
( ) Offset
−
. When tests a capacitive load, current
reading = (real measurement value) – (Offset).
(Real measurement value)
4. GB OFFSET: Please use the standard 4-wires test cable to process
standard resistance test, doesn’t need additional OFFSET operation.
If using with our grounding accessories, the maximum test error is
possible increased to 2mohm. Before Offset test is done, please be
sure offset resistance. When Offset resistance value is lower than
5mohm, do Offset is not recommended. Incorrect Offset may
influence error of real test value.
5. OSC OFFSET: There is stray capacitance on wire or fixture, please
does OFFSET elimination again on changing wire or fixture every time
for ensure the accuracy of testing.
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