Yokogawa EJA530A - Manual (Page 55)

IM 01C21F01-01E 9-6
9. MAINTENANCE
9.5 Troubleshooting
If any abnormality appears in the measured values, use
the troubleshooting flow chart below to isolate and
remedy the problem. Since some problems have
complex causes, these flow charts may not identify all.
If you have difficulty isolating or correcting a problem,
contact Yokogawa service personnel.
9.5.1 Basic Troubleshooting
First determine whether the process variable is actually
abnormal or a problem exists in the measurement
system.
If the problem is in the measurement system, isolate
the problem and decide what corrective action to take.
This transmitter is equipped with a self-diagnostic
function which will be useful in troubleshooting; see
Section 8.5 for information on using this function.
Abnormalities appear in
measurement.
: Areas where self-diagnostic offers support
Is process variable
itself abnormal?
Inspect the
process system.
Isolate problem in
measurement system.
Does problem exist in
receiving instrument?
Check/correct
environmental conditions. Inspect receiver.
Check transmitter.
Check/correct operating
conditions.
Y
Y
N
Measurement system problem
N
Environmental conditions
Operating conditions
Transmitter itself
F0905.EPS
Figure 9.5.1 Basic Flow and Self-Diagnostics
9.5.2 Troubleshooting Flow Charts
Connect BRAIN TERMINAL and check self-diagnostics.
Does the self-diagnostic indicate problem location?
Contact Yokogawa service personnel.
F0906.EPS
Symptoms • There is no output signal.
• Output signal does not change although process variable is known to be varying.
• Output value is inconsistent with value inferred for process variable.
Is power supply polarity correct?
Are power supply voltage and load resistance correct?
Refer to error message summary in
Subsection 8.5.2 to take actions.
YES
NO
NO
YES
Refer to Section 6.3 to check/correct
polarity at each terminal from power
supply to the terminal box.
Fix pressure leaks, paying particular
attention to connections for impulse
piping,pressure-detector section, etc.
Fully close equalizing valve, and fully
open high pressure and low pressure
valves.
Refer to Section 6.6 for rated voltage
and load resistance. NO
YES
NO
YES
YES
NO
Find/correct broken conductor or wiring
error.
NO
YES
Are valves opened or closed correctly?
Is there any pressure leak?
Is there continuity through the transmitter loop wiring?
Do the loop numbers match?