XT2640 Operating Manual
13 July 2016
Page 41 of 187
Changes made in this screen are not used for measurements until the underlying MEAS CONFIG screen is navigated away from.
Note:
If scaling is disabled for voltage and/or current, the scale factors and offset remain saved in the XT2640 for later reuse.
If the channel is subsequently selected in another VPA (or disabled by not selecting it in any VPA) then the channel scaling
and offset settings stay with the channel.
Voltage scale factors between 0.001 and 1000000 may be entered.
Current scale factors between 0.000001 and 1000000 may be entered.
Current offsets may be entered up to the maximum measurable for the current input option and are the offset at the output
of the transducer (as shown on the screen).
The current offset is applied as a DC offset to current measurements. You should not attempt to use it as a method to offset
an unwanted AC signal content.
12.4.2.1.3
Setting
the
Current
Range
for
Channels
Pressing any of the channel A RANGE buttons allows you to configure that channel for the desired current range selection.
Pressing the A RANGE button next to the ALL button sets all selected channels to the same current range selection.
Settings of HI, LO and AUTO may be available depending on the current option in each channel.
Note:
If set for AUTO then the text in the A RANGE button also indicates the present range being used (LO or HI).
Channels having the H current input option have no A RANGE button.
Channels having the X current input option do not allow an AUTO range selection.
Recommendations:
In most applications you should select the same current range for all channels in a VPA.
When configuring a channel with the D current input option the use of the AUTO setting is recommended for most
applications, however if the load has rapidly and widely changing current or if the user is going to trigger on an inrush
current, then the HI range should be selected.
When configuring a channel with the X current input option you should choose the range giving the best compatibility with
the type of transducer being used. Generally, for A:V type transducers this will be the HI range and for external shunts this
will be the LO range.
12.4.2.2
CONFIGURING
THE
MEASUREMENTS
MADE
IN
THE
SELECTED
VPA
This is performed by using the buttons in the MEASURE area. Some of the settings in this area are interdependent, you should start
with the uppermost setting and work downwards on the screen (all lower settings are forced to be consistent with higher settings as
needed).
Note:
Depending on configuration and the installed channels some buttons may not be present or may not allow modification of
the setting.
12.4.2.2.1
Setting
the
Low
Frequency
Limit
and
Measurement
Period
The LF/PERIOD button allows you to select the low frequency limit and measurement period for the selected VPA if MEAS MODE is
not EN61000‐3‐2 or EN61000‐3‐12.
Settings of VLF, LF, 10Hz/0.3s, 20Hz/0.1s, 45Hz/20ms, 150Hz/10ms and 500Hz/2ms are available. Additionally, settings selecting a
lower numbered VPA are available when MEAS MODE is set for MULTI VPA or SYNC VPA and you are configuring VPA2 or VPA3.
Note:
The 500Hz/2ms setting is only available when the VPA is configured with W type channels.
This setting sets the nominal measurement period; the actual measurement period will be automatically adjusted during
operation to be the nearest integer number of fundamental signal cycles as needed.
