Yokogawa EJA118 - Manual (Page 52)

IM 1C22H1-01E 8-5
8. MAINTENANCE
8.5 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.
8.5.1 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 7.5 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.
Measurement system problem
F0804.EPS
YES
NO
NO
YES
Environmental conditions
Operating conditions
Transmitter itself
Figure 8.5.1 Basic Flow and Self-Diagnostics
8.5.2 Troubleshooting Flow Charts
Connect BRAIN TERMINAL and check self-diagnostics.
Does the self-diagnostic
indicate problem location?
Contact Yokogawa service personnel.
F0805.EPS
The following sorts of symptoms indicate that transmitter
may not be operating properly.
Example : • There is no output signal.
• Output signal does not change even though
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 7.5.2 to take actions.
Refer to Section 5.3 to check/correct
polarity at each terminal from power
supply to the terminal box.
Refer to Section 5.6 to obtain rated
voltage and load resistance.
Find/correct broken conductor or
wiring error.
Is there
continuity through the
transmitter loop wiring?
Do the loop numbers
match?
YES
NO
NO
YES
NO
YES
NO
YES