14
Notes:
1. Tighten housing cover (both front and back covers if dual cavity) to
full stop against the O-ring.
2. Do not over-tighten compression fittings.
3. Use side conduit entry only.
4. In high humidity areas, use a breather drain type conduit sealing
fitting to minimize moisture intrusion.
Conduit sealing fitting
NPT or BSPP Fitting
Do not over-tighten
compression fitting!
Interface float
(ordered
separately)
Product float
(ordered
separately)
View shown with
cover removed
Plugged entry
Do not use
(see notes)
3/4 NPT or M20 conduit access
Use NPT conduit fitting only!
Conduit
(flexible or rigid)
Conduit from
control room
Level Plus
®
Do not remove cover with circuit live in
hazardous locations!
Follow safe work procedures.
Level Plus
®
SoClean
®
Operation Manual
7.4 Cable recommendations
Refer to ‘Table 2’ below for general requirements of cable types for
the Level Plus
®
SoClean
®
analog transmitter.
Cable specifications
7.5 Electrical conduit
Table 2: Cable specification and parameters
Fig. 12: Electrical conduit installation
Parameter
Specification
Minimum cable size
24 to 14 AWG (0.51 to 1.6 mm diameter)
Cable type
Single pair shielded or multiple pair with
overall shield; minimum 0.010 in. (0.25
mm) insulation thickness
Capacitance
Less than 30 pF/ft (98 pF/m)
7.6 Grounding
7.6.1 Safety grounding
Warning:
Grounding the transmitter through a threaded conduit connection does
not meet the requirements as a grounding of the sensor for safety.
There are two methods to provide an earth ground to the earth ground of
the electronics. Either method must result in a resistance of less than 1
Ohm. Refer to ’Table 3’ for safety barrier references.
»
Run an earth ground through the conduit and connect directly to the
earth ground lug inside the housing.
»
Run an earth ground directly to the ground lug on the outside of the
housing.
7.6.2 Shield grounding
Warning:
The shield ground does not meet the requirements as grounding of the
sensor for Safety.
Immunity performance of the sensor from external sources of surge,
burst, RF, radiated emissions and other noise is dependent on a proper
ground for the shield of the communications cable.
The communications cable shield should be of a braided type and connec-
ted to the internal ground lug of the sensor housing.
Runs in a continuous metallic conduit
When installed inside a dedicated continuous metallic conduit, the conduit
provides a level of shielding protection from external interference and a
level of ground to the sensor housing. In this case a foil type shielded
cable with a drain wire connected to the internal ground lug may be
sufficient.
Sharing of the metallic conduit with other cables will result in loss of
effective shielding performance of the communication cable and possible
degradation in performance of the sensor. In this case a braided type
shielded cable connected to the sensor internal ground lug would be
recommended.
In all cases paralleling the communications cable
with any noise generating cable inside of a conduit
or with noise generating cables in close proximity to the conduit
may degrade the performance of the sensor
Runs without a conduit
In some rare applications, or where safety may not be required, a metallic
conduit may not exist. The communications cable shield should be of
a braided type and connected to the internal ground lug of the sensor
housing.
Alternatively a safety approved EMC Cable Gland can be used for groun-
ding the shield. Contact MTS for information before using one of these
cable glands.
NEC
Undesirable currents (ground loops) is a violation of the NEC and is a
safety hazard.
