Addendum to User’s Manual
EDI-53 Series Digital Indicator
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Addendum
Model EDI-53ST Digital Indicator for Encardio-rite Model EAN-70 Tilt Meter
1
INTRODUCTION
The EDI-53ST Indicator is a customized version of EDI-53 series indicator that is suitable for use with
Encardio-rite Model EAN-70 Servo accelero-meter type tilt meter.
Except for the differences described below, the EDI-53 Series Digital Indicator User’s Manual [ER
document No. WI-6002.67] is valid for most of the other operations and technical specifications of this
indicator. The section numbers given below refer to the original section numbers of the User’s Manual
that are affected by the change.
2
TRANSDUCERS
The EDI-53ST Indicator is meant for use with Encardio-rite Model EAN-70 servo accelerometer type
tilt meters only. The EAN-70 tilt meter has a measurement range of
±
30
°
from horizontal. It provides
a full-scale output of
±
5.000 V at
±
30
°
. The output voltage is proportional to the sine of the measured
tilt angle rather than the tilt angle in arc degrees. EAN-70 tilt meter requires an excitation supply of
±
12 V, which is supplied by the indicator.
2.1
Measurement of transducer output
The EDI-53 series indicator can measure full scale input voltages only up to
±
2.0 V. So the EAN-70
output voltage is internally attenuated by a factor of 4 to yield a full-scale value of
±
1.25 V. In the
Volts mode the full-scale tilt output from the EAN-70 would be shown as 1.2500 V by the indicator.
2.2
Calculation of parameters value in engineering units
As explained in section 3.2 above, the indicator in volts mode will show the EAN-70 output at 30
degrees as 1.25 V. However, the value of Sin(30
°
) is 0.5000. As the EAN-70 output is linear with sine
of the measured angle, it makes more sense to display the tilt meter output in terms of sine(A) where
A is the angle of tilt.
For the indicator EDI-53ST to show the tilt value in terms of sine of angle, at least one of the channels
of the indicator should be configured with a fixed gage factor (= 4000) and offset value (= 0.0000) as
described in
section 5
below.
The tilt meter output will now appear on the indicator display as Sin(A) x 10000, i.e. sine of the
measured angle measured angle multiplied by a factor of 10,000. The multiplication factor of 10,000 is
often known as the ‘instrument constant’. Consequently, if the measured tilt angle ‘A’ is 30
°
, sin(A) will
be 0.5000 and the indicator display will show 5000.
If the value of tilt angle A is required in arc degrees, the indicator reading ‘x’ can be converted to arc
degrees as follows:
A = sin
-1
(x / 10000)
As the EDI-53ST allows the logged readings to be stored in memory and later down loaded to a
computer, a large number of indicator readings can be easily and quickly converted to corresponding
‘arc degree’ values using any commercially available spreadsheet program like Microsoft Excel.
2.3
Non-linearity correction using polynomial calculation
Polynomial correction is not required for EAN-70 tilt meter output, and hence the correction
coefficients are not provided in the supplied calibration certificates (test report) supplied with individual
