KROHNE Altosonic III, Installation And Operating Instructions Manual

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ALTOSONIC III 28
Maximum input current : Imax = 600 mA
Maximum internal capacitance : Ci = 13.1 nF (maximum, 3 sensor circuits)
Maximum internal inductance : Li = 134 µH (maximum, 3 sensor circuits)
The intrinsically safe sensor circuits of the ALTOSONIC III C/…-EEx compact flowmeter are only internal circuits and
not accessible for the user.
5.4 Flow converter
The UFC III…-EEx flow converter consists of an approved cylindrical housing, made of a stainless steel (type VX-EEx
with PTB No. Ex-96.D.1068 U). It contains two separate compartments, divided from each other by wall with an
integrated encapsulated flameproof terminal feed-through. The housing of the compact version is screwed on top of the
flow sensor, the housing of the separate version is screwed on an aluminium or stainless steel wall-mounting bracket. A
junction box made of stainless steel is screwed to the side of the bracket by four M6 recessed head screws with internal
hexagonal socket set (only applicable for the flow converter in separate design).
The flow converter housing is on both ends closed by a threaded cylindrical cover with O-ring sealing. Coaxial cables of
type RG179 or RG316 with SMB plugs at their ends connect the intrinsically safe sensor output circuits of the flow
converter to the corresponding SMB male-to-male bulkheads in the junction box.
The equipotential bonding conductor is screwed under the external M5 U-clamp terminal, which is located on the
mounting flange at the bottom of the neck of the flow converter housing. The flow converter housing has an ingress
protection degree of at least IP67 in accordance with EN 60529.
Electronics compartment
The electronics compartment accommodates the UFC III…-EEx electronics unit. The compartment is designed with type
of protection flameproof enclosure "d" in accordance with EN 50018. It is closed by a flameproof display cover with
glass window, which is glued and additionally mechanical supported by a screwed in back-up ring made of aluminum or
stainless steel (depends on the material of the housing). The interconnecting part (i.e. neck) at the bottom of the
housing contains a flameproof cable feed-through, through which the coaxial cables run. The feed-through provides a
flameproof sealing at the bottom of the electronics compartment.
The UFC III…-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
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.
“EEx d” approved cable glands are no part of the standard delivery package, but must be provided by the customer
himself or ordered explicitly at KROHNE.
1) Semi-circular insulating cover plate
2) U-clamp terminal size M4 (7 in total)
3) Dividing plate of insulating material (8 in total)
4) Flameproof terminal feed-through