Liquid Controls IT375 - Manual (Page 23)

Sponsler, Inc. Model IT375 Intrinsic Safety Pg. 23
8. INTRINSIC SAFETY CONNECTIONS
When installing the Model IT375 in hazardous areas, the wiring and installation must comply with appropriate
installation standards.
The approval uses entity parameters on the input for connections to the flowmeter and associated apparatus type approval
for the 4-20mA output. The 4-20mA output must, therefore, only be connected to barriers with the specified safety
parameters as shown on the following page.
8.1 COILS
The Model IT375 will connect directly to a turbine flowmeter or paddlewheel with a certified Intrinsically Safe (IS) coil
or other certified IS sensor which produce a pulse input provided they do not exceed the following input parameters:
Ui = 24V
Ii = 20mA
Pi = 320mW
The maximum allowed capacitance and inductance of the pulse or coil including the cabling is:
Cext = 60
µF
Lext = 1.5H
The internal capacitance and inductance of the Model IT375 seen on the input are negligibly small with Ci = 0.002uF
and Li = 0mH. The maximum voltage and current produced by the Model IT375 on its inputs (terminals 1 to 4) are:
Uo = 10.0V (open circuit)
Io = 9.0mA (short circuit)
8.2 SIMPLE APPARATUS
Devices such as reed switches which can be classed as "simple apparatus", as defined in the CENELEC standards
EN50020, can be connected to the Model IT375 without certification.
8.3 NAMUR PROXIMITY SWITCHES
Connection to certified Namur proximity switches is permitted as shown on the following page with the following
maximum input parameters:
Ui = 24V
Ii = 20mA
Pi = 320mW