RST Instruments VW2100, Инструкция по эксплуатации, Страница: 25 / 34

VW2100 Vibrating Wire Piezometer
Instruction Manual
ELM0005P RST Instruments Ltd. Page 25
and ground to facilitate the passing of transients away from the vibrating wire
instrument.
Additional information on surge protection alternatives is available from RST.
Additional sources of information on protecting instruments, junction boxes, and data
logging systems against power surges, transients, and electromagnetic pulses are
listed in available in Appendix F.
6 T
ROUBLESHOOTING
Maintenance and troubleshooting of Vibrating Wire Piezometers is confined to
periodic checks of cable connections and maintenance of terminals. The transducers
themselves are sealed and are not user serviceable. The following are typical
problems with suggested remedial actions.
6.1 VW P
IEZOMETER
F
AILS TO
G
IVE A
R
EADING
1
Check the resistance of the vibrating wire coils by connecting an ohmmeter
across the gauge terminals (red and black wires). Nominal resistance is
approximately 180Ω (±5%), plus cable resistance at approximately 15Ω per 300
m of 22 AWG wire. Ensure to account for the two lengths of 22 AWG wire (i.e.
red wire AND black wire) in this calculation. If the resistance is very high or
infinite, the cable is possibly broken or cut. If the resistance is very low, the
gauge conductors may be shorted.
2
Check the VW2106 Readout Unit with another vibrating wire piezometer to
confirm that the VW2106 Readout Unit is working.
3
The vibrating wire piezometer may have been over-ranged or physically
damaged. Inspect the diaphragm and housing for any obvious damage. Contact
RST Instruments if necessary.
6.2 VW P
IEZOMETER
R
EADING
U
NSTABLE
1
Connect the blue shield drain wire on the vibrating wire readout to the shield wire
of the vibrating wire instrument. In the absence of a shield wire on the vibrating
wire instrument, the blue shield drain wire can be connected to the black or green
wires from the vibrating wire instrument. If this does not result in more stable
readings, proceed to step 2 below.
2
Isolate the vibrating wire readout from ground sources by placing it on a piece of
wood or similar non-conductive material. If this does not result in more stable
readings, proceed to step 3 below.
3
Check for sources of nearby electrical noise such as motors, generators,
antennas, or electrical cables. Move the vibrating wire piezometer cables as far
as possible away from any sources of electrical noise. Filtering and shielding
equipment is likely required if the noise cannot be eliminated. Contact RST for
technical advice.