KROHNE UFM 3030 EEx EN - Manual (Page 9)

UFM 3030 9
The UFC 030…-EEx electronics unit is inserted into the electronics compartment with the help of
two sliding rubbers that position and fixate the unit at the front of the inside of the housing. Two M4
screws mount the unit and a third M4 screw fixates the brass earth strip at the back-end of the front-
end printed circuit board, which contains the integrated voltage/current limiting circuit. The three
screws are screwed to the integrated wall inside the electronics compartment. The on the front-end
PCB integrated voltage/current limiting circuit provides the ultrasonic sensors inside the flow sensor
with type of protection intrinsic safety category "ib" according to EN 50020.
The voltage/current limiting circuit has the following maximum output values:
•
Maximum output voltage : V
O
= 8.15 V
•
Maximum output current : I
O
= 220 mA
•
Maximum allowed external capacitance : C
O
= 1.3 µF
•
Maximum allowed external inductance : L
O
= 0.5 mH
1.4.2 MODIS electronics units
The MODIS electronics units have type designation UFC 030i-EEx and are provided with two
MODIS modules. The modules provide intrinsically safe signal input/output circuits, which are
accessible by the user for connection in the terminal compartment of the flow converter housing.
Three types of modules can be used on the UFC 030i-EEx electronics unit, namely: P-SA (current
output), FA-ST (pulse or status output) and F-PA (fieldbus type Profibus).
A combination of two of the above listed modules is installed on the power supply printed circuit
board of the MODIS versions of the UFC 030…-EEx electronics.
1.4.3 Terminal
compartment
The terminal compartment accommodates seven M4 clamp terminals for connection of the power
supply and the signal in-/output circuits. The terminals are separated from each other by insulation
plates (eight in total, from which one at each end of the row).
The terminal compartment (default in type of protection increased safety “e”) is standard equipped
with two metal cable glands of size M20x1.5 or Pg13.5. The terminal compartment can optionally be
provided as a flameproof enclosure “EEx d”, in which case the customer must use pre-certified
“EEx d” cable glands or conduits.
For flameproof conduit systems, the terminal compartment must have type of protection flameproof
enclosure “d” according to EN 50018. The conduits must be sealed by “EEx d” approved (in
accordance with ATEX 100a directive) sealing devices (i.e. stopping boxes) directly at the conduit
entrances of the as flameproof enclosure “EEx d” performed terminal compartment.
1.4.4 MODIS terminal design
The connections for the intrinsically safe MODIS input/output circuits consist of four M4 U-clamp
terminals, separated from the two power supply terminals by an earthed metal plate, which is
screwed to a non-used M4 U-clamp terminal. Eight dividing plates of insulating material in-between
the seven terminals and at each end of the row separate the terminals from each other and from the
earthed metal housing.
After the power supply cable is connected to the appropriate two terminals, these two terminals are
covered by a semi-circular insulating plate to prevent any possible contact with the intrinsically safe
MODIS conductors. See figure below.