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Section 9: Frequently asked questions (FAQs)
Model 2450 Interactive SourceMeter® Instrument Reference Manual
9-10
2450-901-01 Rev. B/September 2013
What is NPLC?
You can adjust the amount of time that the input signal is measured. This time affects the usable
measurement resolution, the amount of reading noise, and the reading rate of the instrument.
The amount of time is specified in parameters that are based on the number of power line cycles
(PLCs). Each PLC for 60 Hz is 16.67 ms (1/60) and each PLC for 50 Hz is 20 ms (1/50).
The shortest amount of time (0.01 PLC) results in the fastest reading rate, but increases reading
noise and decreases the number of usable digits.
The longest amount of time (10 PLC) provides the lowest reading noise and more resolution, but has
the slowest reading rate.
Settings between the fastest and slowest number of PLCs are a compromise between speed and
noise.
If you change the PLCs, you may want to adjust the displayed digits to reflect the change in usable
digits.
What are the Quick Setup options?
The QUICKSET key opens a screen that provides predefined function, performance, and quick
setups.
The Function button allows you to select the source and measurement functions. These are the same
options that are available through the FUNCTION key
The Performance slider allows you to adjust speed and resolution. As you increase speed, you lower
the amount of resolution. As you increase resolution, you decrease the reading speed. These settings
take effect the next time the output is turned on and measurements are made.
The One-Touch Quick Setups allow you to set the instrument to operate as a Voltmeter, Ammeter,
Ohmmeter, or Power Supply.
When you select a Quick Setup, the instrument turns the output on. Carefully consider and configure
the appropriate output-off state, source, and limits before connecting the Model 2450 to a device that
can deliver energy, such as other voltage sources, batteries, capacitors, or solar cells. Configure the
settings that are recommended for the instrument before making connections to the device. Failure
to consider the output-off state, source, and limits may result in damage to the instrument or to the
device under test (DUT).