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EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
PSI 9000 15U/24U Series
5.3
Calibration
5.3.1
Preface
All PSI 9000 series feature a function to re-adjust the most important output values when doing a calibration and in
case these values have moved out of tolerance. The readjustment is limited to compensate small differences of up
to 2% of the max. value. There are several reasons which could make it necessary to readjust a unit: component
aging, component deterioration, extreme ambient conditions, high frequent use or after a unit has been repaired
on location or a local service centre.
In a cabinet of PSI 9000 15/24U series there can be 2-6 units which each could have a tolerance, either in positive
or negative direction. Hence it is required to calibrate the units separately. While the calibration of the master unit
can be done on the control panel, the slave units can only be calibrated via USB and a software. The calibration
procedure, as described below, refers to the master unit. The actual calibration can be done while the master unit
remains in the cabinet and all slave units are powered off.
In order to determine if a value is out of tolerance, the parameter must be verified first with measurement tools of
high accuracy and with at least half the error of the PSI device. Only then a comparison between values displayed
on the PSI device and true DC output values is possible.
For example, if you want to verify and possibly readjust the output current of model PSI 9080-1020 3U which has
1020 A maximum current, stated with a max. error of 0.2%, you can only do that by using a specific measuring
tool with max. 0.1% error or less. When measuring such high currents, it’s recommended to use a current sensor,
also called current transducer.
5.3.2
Preparation
For a successful calibration and readjustment, a few tools and certain ambient conditions are required:
•
A measurement device (multimeter) for voltage, with a max. error of half the PSI’s voltage error. That measure
-
ment device can also be used to measure the voltage on the current sensor when readjusting the current
•
If the current is also going to be calibrated: a suitable current sensor, ideally specified for at least 1.25 times the
max. output current of the PSI and with a max. error that is half or less than the max. current error of the PSI
device to calibrate
•
Normal ambient temperature of approx. 20-25°C
•
Warmed up PSI unit, which has been run for at least 10 minutes under 50% power
•
One or two adjustable loads, preferably electronic ones, which are capable of consuming at least 102% of the
max. voltage and current of the PSI device and which are calibrated and precise
Before you can start calibrating, a few measures have to be taken:
•
Let the PSI device warm up for at least 10 minutes under 50% load, in connection with the voltage / current source
•
In case the remote sensing input is going to be calibrated, prepare a cable for the remote sensing connector to
DC output, but leave it yet unconnected
•
Abort any form of remote control, deactivate master-slave mode, deactivate R mode (resistance)
•
Connect external measurement device to the DC output or to the current sensor, depending on whether the
voltage is going to be calibrated first or the current
5.3.3
Calibration procedure
After the preparation, the device is ready to be calibrated. From now on, a certain sequence of parameter calibra
-
tion is important. Generally, you don’t need to calibrate all three parameters, but it is recommended to do so.
Important:
When calibrating the output voltage, the remote input “Sense” on the rear of the device has to
be disconnected.
The calibration procedure, as explained below, is an example with model PSI 9080-1020 3U. Other models are
treated the same way, with values according to the particular PSI model and the required load.
