KROHNE ALTOSONIC V EEx EN - Manual (Page 7)

ALTOSONIC V 3
Both consist of an approved flameproof box, in which five UFC 500…-EEx electronics units
and the connecting terminals are installed. The low-temperature version is additionally
provided with a heating element of maximum 200 W power, which is controlled by a
thermostat to keep the temperature inside the flameproof box above -20°C. The standard (-
20°C) version can optionally be provided with a heating element of maximum 30 W and
thermostat, to prevent condensation inside the flameproof box.
The UFC 500…-EEx electronics unit can be equipped with one of the following linear power
supplies:
• 115/230 Vac ±13%, 48 – 63 Hz, 12 VA
• 100/200 Vac -15%/+10%, 48 – 63 Hz, 12 VA
• 24/48 Vac ±13%, 48 – 63 Hz, 12 VA
Or with the switching mode power supply of 24 Vac/dc -25%/+33%, 8 W.
All five UFC 500…-EEx electronics units must have the same power supply version. Each
unit is also provided with a RS 485 communication module.
Each UFC 500…-EEx electronics unit drives two of the four intrinsically safe "ib" ultrasonic
sensor circuits that form one measuring line (i.e. two opposite ultrasonic transducers) of the
UFS 500 F/5STR-EEx Flow Sensor. The intrinsically safe output circuits each has the
following maximum values (i.e. entity parameters):
• Maximum output voltage
: V
o
= 8.7 V
• Maximum output current : I
o
= 360 mA
• Maximum allowed external capacitance : C
o
= 1.2 µF
• Maximum allowed external inductance : L
o
= 0.17 mH
1.3.2 Cable and conduit entries
The connecting cables for power supply of the five UFC 500…-EEx electronics units, the
heating element with thermostat (only applies to LT-version) and the RS 485 communication
module either run through ATEX-approved flameproof "EEx d" cable glands or rigid metal
conduits. The rigid conduits must be sealed by ATEX-approved flameproof sealing devices
(i.e. stopping boxes) directly at the entrances of the flameproof box. All non-used openings
must be sealed by ATEX-approved flameproof blind plugs.
1.3.3 Warning messages
The stainless steel data plate of all UFC-V/…-EEx versions is permanently attached to the
cover of the flameproof approved box by four stainless steel rivets and contains following
warning messages (see Appendix 3):
• DO NOT OPEN "EEx d" ENCLOSURE WHILE ENERGIZED. WAIT AT LEAST 30
MINUTES AFTER DE-ENERGIZING.
• ONLY CABLE GLANDS OF "EEx d" APPROVED TYPE IN ACCORDANCE WITH EN
50018 MAY BE INSTALLED!
• WHEN RIGID CONDUITS ARE USED, THEY MUST BE SEALED BY PRE-CERTIFIED
"EEx d" SEALING DEVICES DIRECTLY AT THE ENCLOSURE WALL!
1.3.4 Heating element and thermostats
The UFC-V/LT-EEx Ultrasonic Flow Converter for low ambient temperatures ranging from
-55°C/-50°C up to and including +60°C is provided with a heating element of maximum
200 W and two thermostats T1 and T2, securing a good functioning of the five
UFC 500…-EEx units at "extreme" low ambient temperatures (below -20°C). Thermostat T1
can be set from +5°C to +55°C. It is set at +5°C, which means that the heating element will
continue to heat up the air in the box until it reaches a temperature of +5°C, at which
thermostat T1 will interrupt the power supply of the heating element.