Delta-T Devices SWS User manual

User Manual for the
Surface Wetness
Sensor type SWS
DELTA
-
T DEVICES
SWS-UM-1.2

BURRAGE SURFACE WETNESS SENSOR
USER INSTRUCTIONS
INTRODUCTION
The wetness sensor is a low-power electronic device for measuring
surface moisture.
It works by detecting the change in resistance
across exposed carbon electrodes when the$/ get wet. When used
with the Delta Logger the output is 0
V when dry and > 1 V when
wet.
SPECIFICATIONS
output
: 0 V dry, > 1 V wet
Power requirement
: 5 mA at 7-18 V DC
Active area : Approx 30 by 15 mm
Probe size : 150 mm long, 20 mm dia
Cable
: 2 m
INSTALLATION
The sensors active surface can be mounted horizontally, and
facing upwards, or at any other appropriate angle.
It can be
powered from the logger's own batteries via one of the two warm
up relays (channels 63
& 64), or from an external supply.
Refer to Figure
1 for instructions on the connections of the
wiring. Refer to Figure 2 for instructions on how to connect the
logger's batteries to channels 63 or 64.
CONFIGURING
THE LOGGER
Configure the input channel to measure voltage (VLT), and the
relay channel (63 or 64) as a warm-up channel (WRM) with a
1
second warm-up period, and with the same sampling period as the
input channel.
MAINTENANCE
If the active surface becomes dirty it will give a constant high
output.
It should be cleaned gently with water and a soft
brush.
LWS-UM-01~- Page 1

FIG 1 : WIRING CONNECTION TO THE DELTA LOGGER
WARM=UP
CHANNEL
INPUT
CHANNEL
Actlve
Surf ace
15+
15-
GND
FIG 2 : INTERNAL JUMPER CONNECTION
Channel 63
Channel 64
Page 2

GUARANTEES, REPAIRS AND SPARES
Instruments manufactured by Delta-T are guaranteed for one year
against defects in manufacture or materials used. The guarantee
does not cover damage through misuse or inexpert servicing, or
other circumstances beyond our control.
For Great Britain this means that no charges are made for labour
materials or return carriage for guarantee repairs.
For other countries, the guarantee covers free exchange of faulty
parts during the guarantee period.
Alternatively,
if the equipment is returned to us for guarantee
repair, we make no charge for labour or materials but we do
charge for carriage and
U.K. customs clearance.
We strongly prefer to have such repairs discussed with us first,
and
if we agree that the equipment does need to be returned, we
may at our discretion waive these charges.
SERVICE AND SPARES
We recognise that some users of our instruments may not have easy
access to technically specialised backup.
Spare parts for our own instruments can be supplied from our
works. These can normally be despatched within
1 working day of
receiving an order.
Spare parts and accessories for sensors not manufactured by Delta
T, but supplied as part of the weather station, may be obtained
from the original manufacturer. We
will endeavour to obtain
parts
if requested, but a certain amount of additional delay is
i nevitab1e.
Should
it prove necessary, instruments may be returned to our
works for servicing. We normal1y expect to complete repairs of
our own instruments within
2 days of receiving the equipment.
Other manufacturers' sensors supplied by us and returned for
servicing
will take longer. They will have to be returned to the
original manufacture for servicing, and may be subject to
additional delays of two to four weeks.
Users in countries which have a Delta-T Agent or Technical should
contact them in the first instance.
DELTA-T DEVICES LTD
128 Low Road. Bumell, CambridgeCB5 OEJ, England
Telephone: Newmarket (STD code 0638)742922
Telex: 817670 ASABSE G "ATTN DELTA-T"
Reg. No.
22804R V.A.T. No. 368 3613 32
Page 3
Our FAX number is
(0638) 7431 55