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However, the system is
not
generally
upwards
compatible. ie., you will
not generally be able to use a larger head with the rack electronics from
a smaller system. If you want to expand the measuring range of your
system by using a larger transducer head, please consult your local LEM
SA Sales representative to obtain information on existing options and
cost.
4.3
Custom transducer heads
For current measurement of 10 kA and beyond certain customizing may be
required. Your local LEM SA Sales representative will be able to assist you
with custom requirements for conversion ratio, programmability options etc.
4.4
Voltage output module
In addition to the different transducer heads a system can also be equipped
with a VOM (
V
oltage
O
utput
M
odule). This module will convert the output
current to an output voltage of ± 10 V (nominal full-scale).
Two types VOMs are available, one for each nominal output current range (1
or 2 A). In all cases, the output current is also available for monitoring either
by the 4 mm banana jacks on the back panel or with the Analog Output Cable.
If you have ordered your system with the “B” option (eg. ITZ 5000-S
B
), it
already has a VOM installed. If your system was ordered as a standard
current output system you can have a VOM retrofitted. Please contact your
local LEM SA Sales representative to obtain information on existing options
and cost.
4.5
Current conversion ratio and programmability
The system can generally be considered as a
“current transformer also
working at DC”.
The primary winding is the wire through the center hole of the
head, and the secondary winding is the compensation winding of the
transducer head. The ratio between these two windings defines the current
conversion ratio (
K
N
) of the system.
The smaller transducer heads come with a programming option.
As the nominal output current (1, 2 or 3 A) is fixed (defined by the transducer
head) and the maximum input current
I
PM
can be changed using a
programming plug, the current conversion ratio can be changed enabling the
user to program the system to many different maximum input currents.