Yokogawa digitalYEWFLO (DY) - Manual (Page 94)

TROUBLESHOOTING
IM 1F2B4-01-YIA
Page 89
6.2 O PERATING P ROCEDURES
The Vortex shedding flowmeter is a frequency measuring device. The frequency is generated as
described in the ‘Principle of Operation’ section, and is linear and proportional to flow velocity. The
electronics convert this frequency into a flow rate signal suitable for your process, providing either an
Analog 4-20 mA or powered voltage pulse output.
This troubleshooting section is designed to familiarize you with the electronic circuit, and internal
software operation.
Operating range:
Before proceeding, double check your process conditions and insure that the desired flow rate is within
the operating range, greater than minimum (Qmin) and less than maximum (Qmax). Please reference
the YEWFLO sizing program, or refer to section 1.4 Basic Sizing.
Electronic Circuit Operation:
If the operating flow rate is above Qmin, the vortex shedder with a piezoelectric sensor assembly
should generate a frequency signal proportional to flow rate.
The following circuit configuration is a simplified block diagram of the actual circuit. Some details
are left out for clarity.
Figure 6.2.1: Circuit Configuration