XT2640 Operating Manual
13 July 2016
Page 46 of 187
The SCALE button (if shown) allows you set the scaling to apply to the measurement of the selected source of the torque
measurement.
The OFFSET button (if shown) allows you set the offset to apply to the measurement of the selected source of the torque
measurement.
Note:
For simplicity, the descriptions above assume that a motor is being measured. Measurement of a generator is identical
with the respective similar meanings for each button.
The SCALE and OFFSET buttons allow entries of any value with either polarity.
12.4.3.3
OVERALL
CONFIGURATION
OF
MECHANICAL
MEASUREMENTS
The overall configuration of mechanical measurements is configured using the buttons in the OVERALL area shown on the screen.
The PERIOD button allows you to select the measurement period for speed and torque measurements.
Settings of 10ms, 30ms, 100ms, 300ms, 1s, 3s, 10s, 30s, 100s, VPA1 SYNC, VPA2 SYNC, and VPA3 SYNC are available.
If you select a time period of less than 1 second then the measurement period will be a minimum of the selected time. If
either (or both) digital inputs of speed and torque have a period of longer than this but less than 1 second then the
measurement period (for both speed and torque) is automatically extended to allow measurement of that frequency.
If you select a time period of greater than 1 second then this sets both the measurement period and also the minimum
measurable frequency (i.e. the maximum period) for digital inputs of speed and/or torque.
If you select an electrical VPA then the measurement is selected to be synchronous with the selected VPA.
Note:
If you select to synchronize mechanical measurements to a VPA which has no channels selected then there will be
no measurements of mechanical speed or torque.
Recommendation:
Where the electrical power of the drive (for a motor) or the generated energy (for a generator) is being measured
in a VPA in the XT2640 then that VPA is usually selected for the PERIOD setting. This ensures that the related
electrical and mechanical power measurements are made over the same periods of time.
The DIGITS button allows you to select that all mechanical measurement results will be displayed with limited resolution if desired.
Settings of 3, 4, 5 and 6 are available.
Note:
This only affects displayed numerical results; it does not affect any measurements obtained via an interface or via
a historically saved record or via data logging.
Recommendation:
In most applications this should be set to 5 or 6, if there is significant instability in the signals this should be set to
3 or 4.
The EFF/LOSS button allows you to select how the mechanical power (if available) is included in efficiency and power loss data.
The XT2640 allows mechanical power to be included in one of three available data; IN, MIDDLE and OUT power.
Alternately it can be excluded from all three of these.
12.4.4
IMPORTING,
EXPORTING
OR
RECORDING
THE
MEASUREMENT
CONFIGURATION
The methods for performing this are fully described in section 23.
The measurement configuration can be imported from or exported to a binary file on an external USB drive attached to the front
panel USB port.
Notes:
This file contains almost the entire configuration of the XT2640 (measurements, screens, harmonics limits, custom screen
definition, and preferences). It does not include the interface configuration or the POWER CTRL preference setting.
You can have an almost unlimited number of configurations available to you by creating, exporting and importing them
using a USB Drive in this manner.
Briefly, this is performed by –
1.
Insert the drive into the front panel USB port and wait for it to be READY.
2.
Press the DRIVE INFO area of the screen, the screen shows the file export/import screen.
3.
To export (save) a binary configuration file –
a.
Press the CONFIGURATION button. The screen changes to allowing you to enter a file name.
b.
Enter the desired file name (the extension is automatically provided).
c.
If the file already exists then you are prompted to respond if you wish to overwrite it or not.
d.
The file is then written.
4.
To import (load) a previously exported binary configuration file –
a.
Press the IMPORT button in the right side of this screen, the screen shows the file import screen.
b.
Press the CONFIGURATION button. The right area of the screen shows a list of the available configuration files.
c.
Press the desired file button. The file is then imported and the new configuration is immediately active.
