Michell Instruments Easidew PRO, User Manual

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I.S. Field Display User’s Manual
Michell Instruments 13
OPERATION
3.1.5 Re-Range Display or Calibrate Using an External Current Source: ‘
CAL
’
This function enables the zero and span of the I.S. Field Display to be adjusted using
an external calibrated current source. When used with an accurate traceable current
source this is the preferred method of calibration.
ZEro (Zero)
is the display with 4 mA input
SPAn (Span)
is the display with 20 mA input
To calibrate the I.S. Field Display:
ZEro
1. Select
CAL
from the Con fi guration Menu and press
P
. The instrument will
display
ZEro
which is a request for a 4 mA input current.
2. Adjust the external current calibrator to 4.000 mA and press
P
to reveal
the current zero display.
3. The fl ashing digit of the display can be changed by pressing

or

.
4. When set as required, press
P
to transfer control to the next digit.
5. When all the digits have been adjusted, press
E
to enter the new zero
display and return to the
ZEro
prompt.
SPAn
6. Pressing

from the
ZEro
prompt will cause the instrument to display
SPAn
which is a request for a 20 mA input current.
7. Adjust the external current calibrator to 20.000 mA and press
P
to reveal
the current span display.
8. The fl ashing digit of the display can be changed by pressing

or

.
9. When set as required, press
P
to transfer control to the next digit.
10. When all the digits have been adjusted, press
E
to enter the new span
and return to the
SPAn
prompt.
11. Press
E
to return to the Con fi guration Menu.
NOTES :
• The I.S. Field Display input current must be adjusted to the required
value before the zero and span functions are entered, by pressing
P
.
• Indicators may be calibrated at currents other than 4 and 20 mA, within
the range 3.8 to 21.0 mA, providing the difference between the two
currents is greater than 4 mA. If these conditions are not complied with,
the I.S. Field Display displays
FaiL
and aborts the calibration.
• If the zero current is greater than the span current the instrument will
be reverse acting, i.e. an increasing input current will cause the display
to decrease.