MU300 Rev1.0 Oct20
Page 27 of 54
However, when 0-4-20mA output is used while considering the flow direction, you should
consider two different conditions; when the flow direction is reverse, the output current is
0~4mA; when it is forward, the output current is 4~20mA.
“Check” in M32 menu is used for check whether the current loop has been “calibrated” or not.
Detailed operation steps:
Use [ ][ ] key to switch among “Check 4mA", "Check 8mA", "Check 16mA", "Check 20mA"
readings. At the same time, use the precisive ammeter to measure the output current of the
current loop, calculate the difference between them and check whether it is in the tolerance or
not. You could calibrate 4-20mA in M62 menu.
Note
The integrated pulse should be appropriate; if it is too big, the output period would be
too long; If it is too small, the relay would operate too frequently, which would
influence its service life; and when it is too fast, it would generate pulse loss. It is
recommened to apply 1-3 pulse output/sec.
6.1.9 Alarms
Switch output alarm signal is generated through switching on/off OCTs or relays and output to
the external circuit, it is generated under the following conditions:
1.
Transducers can’t receive ultrasound signals;
2.
Ultrasound signals that transducers received are too poor;
3.
The flowmeter is not under normal operation;
4.
The flow is reversed;
5.
The analogue output exceeds 100% of the measuring range;
6.
The frequency signal exceeds 120% of the measuring range;
7.
Transient flow exceeds the settings (use software alarm to set the range of flow. There are
two software alarms, which are Alarm #1 and Alarm #2T respectively.
How to set? For example 1: It requires the relay outputs alarm signals when the transient flow
exceeds 300~1,000m3/h, settings are as follows:
(1)
Menu 35, Alarm 1#, lower limit300;
(2)
Menu 35, Alarm 1#, upper limit1,000;
(3)
Menu 34, Relay Settings-Options-Alarm 1#.
