Greyline Instruments OCF 5.0, User Manual

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Page 27
OCF 5.0 Open Channel Flow Monitor
C - sensor cable extended and junction not
insulated
- Use metal Junction Box
C - through enclosure - use metal enclosure
C - through 4-20mA output cable - use shielded twisted pair (shielded to AC ground)
- use grounded metal conduit
C - wiring or installation close to variable
speed drive or inverter
- follow V.S.D. manufacturer’s instructions for Drive
grounding, wiring and shielding
Unit Receives No Return Echo Due To:
C,F,E - foam on liquid surface - use stilling well (open channel flow)
B - target beyond Max Range - recalibrate
F - sensor damaged - remove sensor from mounting and aim at a flat,
stable target to test
F - sensor misalignment - check with a level
Wiring Problems Due To Sensor Cable:
A,C,F, - open circuit - check connections/continuity (8850 to 12700 ohms
max./-30°C to +70°C )
B,F - short circuit - check connections/continuity (8850 ohms min.)
F - too long (max 500 ft., 150 m)
C - bundled/run in conduit with power cable
C - sensor ground shorted to conduit/enclosure - insulate
A - extended with wrong type of wire - use RG62A/U coaxial only
C - close to high voltage/large motors
C - AC chassis/ground missing on instrument
power connections
Non-Linearity Due To:
H - vapour - dissipate fumes, Calibration in-situ
H - zero not set accurately - see “Zero Positioning of Sensor”
H - wrong flume, or K&n selected (
FLOW
mode)
- select correct flume
- temperature measurement inaccuracy - install sensor sunscreen
- mount sensor closer to flow