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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
EL 9000 B 15U/24U Series
5.3
Calibration
5.3.1 Preface
The devices of this series feature a function to re-adjust the most important DC input related values, which can
help in case these values are out of tolerance. The procedure is limited to compensate small differences 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 a cabinet there can be 3-6 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 vian USB and a software (available upon request). 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 EL device. Only then a comparison between values displayed
on the EL device and true DC input values is possible.
For example, if you want to verify and possibly readjust the input current of unit model EL 9080-510 B (the model
name is printed on the front) 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 recom
-
mended 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.
5.3.2 Preparation
For a successful calibration and re-adjustment, a few tools and certain ambient conditions are required:
•
A measurement device (multimeter) for voltage, with a max. error of half the EL’s voltage tolerance. That meas
-
urement device can also be used to measure the shunt voltage when re-adjusting the current
•
If the current is also going to be calibrated: a suitable DC current shunt, ideally specified for at least 1.25 times the
max. input current of the EL and with a max. error that is half or less than the max. current error of the EL device
•
Normal ambient temperature of approx. 20-25 °C
•
An adjustable voltage & current source which is capable of providing at least 102% of the max. voltage and cur
-
rent of the EL device, or separate voltage source and current source units
Before starting the calibration procedure, a few measures have to be taken:
•
Let the EL device warm up for at least 10 minutes under 50% power, 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 input, but leave it yet unconnected
•
Abort any form of remote control and set device to
U/I
mode
•
Install the shunt between source and EL device and make sure the shunt is cooled somehow. For example ,
you might want to place it in the warm air stream coming out of the rear of the EL device. This helps the shunt
to warm up as well to operation temperature
•
Connect suitable measurement devices to the DC input and to the shunt, 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:
The input current calibration should be done before any voltage calibration, because the cali
-
brated input current is used for voltage calibration.
When calibrating the input voltage, the remote input sense on the rear of the device has to be
disconnected.
The calibration procedure, as explained below, is an example for a master unit model EL 9080-510 B (the unit
model is printed on the front of every unit). Other master unit models from other cabinet models are treated the
same way, with values according to the particular master unit model and the required power source.
