Instructions

Page 69
EA Elektro-Automatik GmbH
Helmholtzstr. 31-37 • 41747 Viersen
Germany
Fon: +49 2162 / 3785-0
Fax: +49 2162 / 16230
www.elektroautomatik.de
[e-mail]
PS 9000 3U Series
4.3 Calibration (readjustment)
4.3.1 Preface
The devices of series PS 9000 feature a function to re-adjust the most important DC output related values, which
can help in case these values are out of tolerance. The procedure is limited to compensate small di󰀨erences of up
to 1% or 2% of the ratings. There are several reasons which could make it necessary to readjust a unit: component
aging, component deterioration, extreme ambient conditions, high frequent use.
In order to determine if a value is out of tolerance, the parameter must be veried rst with measurement tools of
high accuracy and with at least half the error of the PS device. Only then a comparison between values displayed
on the PS device and true DC output values is possible.
For example, if you want to verify and possibly readjust the output current of model PS 9080-510 3U which has
510 A maximum current, stated with a max. error of 0.2%, you can only do that by using a high current shunt with
max. 0.1% error or less. Also, when measuring such high currents, it is recommended to keep the process short,
in order to avoid the shunt heating up too much. It is furthermore recommended to use a shunt with at least 25%
reserve.
When measuring the current with a shunt, the measurement error of the multimeter on the shunt adds to the error
of the shunt and the sum of both must not exceed the max. error of the device under calibration.
4.3.2 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 PS’s voltage error. That measurement
device can also be used to measure the shunt voltage when readjusting the current
• If the current is also going to be calibrated: a suitable DC current shunt, ideally specied for at least 1.25 times the
max. output current of the PS and with a max. error that is half or less than the max. current error of the PS device
• Normal ambient temperature of approx. 20-25°C (68-77°F)
• An adjustable load, such as an electronic load, which is capable of consuming at least 102% of the max. voltage
and current of the PS device
Before you can start calibrating, a few measures have to be taken:
• Let the PS device warm up 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, set device to U/I mode
• Install the shunt between PS device and load and make sure the shunt is cooled somehow
• Connect external measurement device to the DC output or to the shunt, depending on whether the voltage is
going to be calibrated rst or the current
4.3.3 Calibration procedure
After the preparation, the device is ready to be calibrated. From now on, a certain sequence of parameter cali-
bration is important. Generally, you don’t need to calibrate all three parameters, but it is recommended to do so.
Important:
• It is recommended to do the calibration of current before any voltage calibration
• When calibrating the voltage, the input “Sense” on the rear of the device must be disconnected
• During the calibration, the user is asked to enter measured values. If these value dier too
much from the value measured by the device or wrong values are entered, the calibration
fails and has to be repeated.
The calibration procedure, as explained below, is an example with model PS 9080-170 3U. Other models are
treated the same way, with values according to the particular PS model and the required load.