PSI System Controls and Diagnostics
I128r5 User Manual
I128r5_UM_190923 Page 118 of 123
Figure 74. Fan power connector (2 pin Molex)
The I128r5 is fitted with a 1.1 amp automatically resetting positive temperature coefficient
(PTC) fuse in the 24 VDC input. No user intervention is required if the fuse operates due to
overcurrent. The fuse will reset when the overcurrent condition ends.
30.2 Calibration
Run the internal calibration function of the I128r5 periodically. Make sure there are no signals
present at the inputs when doing this. It is good practice to note any changes in the gain and
offset parameters, because any trend would indicate that the affected channel might be out of
specification.
Depending upon your application and your operational procedures, you may need to check the
accuracy of the I128r5 against an external traceable current standard periodically. This is
particularly the case for the high current channel (HCC) which is typically used for dosimetry.
External calibration can be done with any suitably-rated true current source such as the models
available from Keithley. Since the I128r5 has high inherent accuracy, you must ensure that your
reference source is in calibration. The compliance voltage of the reference source should be set
to between 1.00 and 5.00 V, and you should ensure that there is a well-defined current return
path from the I128r5 back to the source.
Pyramid Technical Consultants Inc. offers a back to base calibration service for the I128r5.
