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I.S. Field Display User’s Manual
28 97321 Issue 2.3, May 2016
MAINTENANCE
4 MAINTENANCE
4.1 Fault Finding During Commissioning
If the I.S. Field Display fails to function during commissioning, the following procedure
should be followed:
Symptom Cause Solution
No display Incorrect wiring
Check wiring
There should be 0.6 to 1.2 V between terminals 1 &
3 with terminal 1 positive
With an optional loop-powered backlight, there
should be 3.4 to 5 V between terminals 1 & 13 with
terminal 1 positive
No display 0 V between
terminals 1 & 3
Incorrect wiring or no
power supply
Check supply voltage and voltage drop caused by all
the instruments in the loop
All decimal points fl ashing Under range if –ve sign
displayed or over range
Recalibrate the numerical display
Unstable display 4-20 mA input is noisy
Eliminate ripple on 4-20 mA power supply and/or
decrease resolution
Unable to enter
Con fi guration Menu
Incorrect security code
entered
Enter correct security code, or contact Michell
Instruments if the code has been lost
4.2 Fault Finding After Commissioning
!
Ensure plant safety before starting maintenance.
Live maintenance is permitted on intrinsically safe equipment installed in a gas hazardous
area, but only certi fi ed test equipment should be used unless a gas clearance certi fi cate
is available.
If an I.S. Field Display fails after it has been functioning correctly follow the procedure
shown in Section 4.1. If this does not reveal the cause of the fault, it is recommended
that the instrument is replaced. This can be done without disconnecting power, but
while the I.S. Field Display is disconnected the 4-20 mA loop will be open circuit.
4.3 Servicing
All I.S. Field Displays are interchangeable if the required optional backlight and
alarms are fi tted. A single spare instrument may quickly be recalibrated to replace any
instrument that is damaged or fails. No attempt should be made to repair instruments
at component level.
It is recommended that faulty instruments are returned to Michell Instruments or to a
local Michell Instrument's agent for repair.
4.4 Routine Maintenance
The mechanical condition of the instrument and electrical calibration should be regularly
checked. The interval between inspections depends upon environmental conditions. It
is recommended that, initially, instrument calibration should be checked annually.