Measurement Specialties
KPSI
®
Digital Series User’s Manual
Page 4
www.Meas-Spec.com
C a b l i n g a n d W i r i n g
Most installations using the transducer connect our polyurethane or Tefzel
®
cable to a junction
box. From this junction box, users run their own cable to the required instrumentation.
Polyurethane is used for most applications while Tefzel
®
is recommended for highly corrosive
environments. The transducers are intended for applications with requirements that include
battery-powered operation with minimal current drain, low system cost, and use of a single
recorder with multiple sensors attached. It will accommodate cable lengths between sensors
and recorder up to 200 feet.
The vented cable termination end is prepared at the factory to eliminate future moisture
migration down its length. It may be noticed where the lead wires emerge from under the
jacket, that potting material plus a shrink tube “boot” have been added. Every effort should be
made to leave this feature intact. Should the cable be longer than is needed for your
installation, it is recommended that the excess length be accommodated in a service loop and
that the potted end of the cable
NOT
be shortened.
The cable attached to your transducer is specifically engineered for submersible applications.
The outer jacket provides long term reliability under most conditions. The cable should be
handled carefully, however, as the jacket may be subject to cutting should it be “raked” over
extremely sharp edges. To guard against water incursion should an inadvertent cut occur, we
have incorporated an exclusive “water block” feature immediately beneath the jacket. This
feature makes the cable “self-sealing” in all but the most extreme cases. The cable is fully
shielded, with the shield connected to the metal housing at the transducer end and terminated in
a blue-insulated wire at the termination end. The shield should always be terminated to a good
earth ground,
unless
the transducer is installed in an area where electrolysis corrosion is known
to be a serious problem.
Surge/lightning protection is offered as an option for your transducer. This is achieved through
the use of two (2) separate protectors. One is located in a 4-inch long housing extension
attached directly to the non-pressure-sensing end of the transducer. The other protector is
located at the surface and grounded via a DIN-rail or ground wire. Whether lightning protection
is employed or not, the cable shield is left exposed (as mentioned previously) so that the shield
may be attached to an earth ground.
sdi-12 wiring
Only three wires are needed to use the SDI-12 interface. A fourth wire (cable shield — blue) is
added for user convenience.
1.
Serial data (white) — SDI-12 interface between sensors and data recorders.
2.
Ground (black) — Supply return and earth ground.
3.
Supply (red) — This line is internally regulated and can accept 8-28 VDC.
