Yokogawa RAMC User Manual
Page 45
<6. ELECTRONIC TRANSMITTER (-E)>
6-19
IM 01R01B02-00E-E 10th edition January 01, 2013 -00
All Rights Reserved. Copyright © 2003, Rota Yokogawa
Autozero with flow
The Autozero function can be carried out also under flow, if the flow cannot be switched off. To this the
following expiry is recommended:
- Plant in operation (measuring tube filled with medium)
- Move flow to constant value (preferably between 10% and 40%)
- Fix pointer on the oriented scale factor with adhesive tapes or underlayed paper stripe
- Start Autozero function by menu.
- Check Autozero value after approx. 80 seconds.
It has to be respected on this absolutely, for this the flow is constant during the Autozero duration!
Normally at this variant higher Autozero results must be expected !
Autozero range
The factory default autozero value is zero (0.000).
At the inquiry of the autozero value it has to be respected that the pointer / tap system are not in the rest
position. In this case the autozero value is zero and the Float-Move-Detection does not work.
Normally the autozero value is smaller than 0.200. If higher results should appear in the application, a multiple
inquiry of the autozero value is recommended to confirm the value.
Supervision range (measuring range)
The measuring range in which Float-Move-Detection is active lies between 5% and 105% of the maximum flow
Qmax (Factory Setting). With the help of the function “F72” this range can be reduced if a supervision is not
possible or not desired in the lower flow range. The range can be restricted to 15% or 30% to 105% (see
point 3.1 to 3.3).
Supervision time (Time Out)
The supervision time of the measuring signal is 5 minutes (Factory Setting). If the measuring signal should not
exceed the autozero value during this period, this is recognized as blockade and an error condition is shown.
The supervision time can be increased with the function “F73” up to 15 minutes.
Indication of a blocking condition
After the recognition of the blockade the error code “08” is produced and the bars under the displayed
measurement value are flashing (see fault behavior). Simultaneously the current output is set to a value, which
enables a clear fault detection of a connected evaluation unit :
- 2 - wire 4-20 mA: Error condition: IA (IG) < 3.6 mA
- 3 - wire 4-20 mA: Error condition: IA < 0.0 mA
- 3 - wire 0-20 mA: Error condition: IA = 0.0 mA