SMAR TT302, Installation, Operation & Maintenance Instruction Manual

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Section 4
4-1
Maintenance Procedures
Troubleshouting
SMAR TT302 transmitters are extensively tested and inspected before delivery to the end
user. Nevertheless, during their design and development, consideration was given to the
possibility of repairs being made by the end user, if necessary.
In general, it is recommended that end users do not try to repair printed circuit boards.
Spare circuit boards may be ordered from
SMAR whenever necessary.
SYMPTOM PROBABLE SOURCE OF PROBLEM
ƒ
Transmitter Connections
Check wiring polarity and continuity.
Check for shorts or ground loops.
Check if the power supply connector is connected to main board.
Check if the shield is not used as a conductor.
It should be grounded at one end only.
ƒ
Power Supply
Check power supply output. The voltage must be between 9 - 32 VDC at the TT302 terminals. Noise
and ripple should be within the following limits:
a) 16 mV peak to peak from 7.8 to 39 KHz.
b) 2 V peak to peak from 47 to 63 Hz for non-intrinsic safety applications and 0.2 V for intrinsic safety
applications.
c) 1.6 V peak to peak from 3.9 MHz to 125 MHz.
ƒ
Network Connection
Check that the topology is correct and all devices are connected in parallel.
Check that two Terminators are OK and correctly positioned.
Check that the Terminators are according to the specifications.
Check length of trunk and spurs.
Check spacing between couplers.
ƒƒƒƒ
Network Configuration
Make sure the device tag is configured if system configuration is desidered.
Make sure that device address, connection and index for all variables are configured correctly if pre-
configuration is used.
NO COMMUNICATION
ƒ
Electronic Circuit Failure
Check the main board for defect by replacing it with a spare one.
ƒ
Transmitter Connections
Check for intermittent short circuits, open circuits and grounding problems.
Check if the sensor is correctly connected to the
TT302 terminal block.
Check if the sensor signal is reaching the TT302 terminal block by measuring it with a multimeter at the
transmitter- end. For mV and thermocouples test can be done with connected and disconnected to the
transmitter.
ƒ
Noise, Oscillation
Adjust damping
Check grounding of the transmitters housing, extra important for mV and thermocouple input.
Check the terminal block for moisture.
Check that the shielding of the wires between sensor/transmitter and transmitter / panel is grounded
only in one end.
INCORRECT READING
ƒ
Sensor
Check the sensor operation; it shall be within its characteristics.
Check sensor type; it shall be the type and standard that the
TT302 has been configured to.
Check if process is within the range of the sensor and the TT302 .
ƒ
Electronic Circuit Failure
Check the integrity of circuit replacing it with a spare one.
INCORRECT READING
ƒ
Transmitter Configuration
Check if the sensor and wires configuration are correct.
Table 4.1 - Messages of Errors and Potential Cause