Special Lock; Cable Entries / Sealing Plugs; Power Supply; I/O Functions - KROHNE H250/M10 Installation And Operating Instructions Manual

3.4

Special lock

The sealing covers of the electronics compartment are secured by a special lock. The locking
screw requires use of an Allen key (3 mm size).
3.5

Cable entries / sealing plugs

The H..../..../M10 variable-area flowmeter with Cat. II3D is provided alternatively with one or two
cable entries. These parts provide for a contaminat and water protection (degree of protection) of
IP65 acc. to EN 60529, NEMA 4x at a temperature range of T
size of the cable entries is 6...12mm.
3.6

Power supply

The H..../..../M10 variable-area flowmeter with Cat. II3D do not require any separate power source.
The necessary supply is obtained via the current output 4 ... 20 mA.
3.7

I/O functions

When connecting the I/O interfaces of the H..../..../M10-EEx variable-area flowmeters, the
following values need to be taken into account.
I/O function (1)
See Standard Installation
and Operating Instructions
(1) Only for connection to circuits with "functional extra-low voltage with protective separation (PELV)"
Peak values U ≤ 25V ; U
AC
3.8

Ambient temperature / Process temperature

The permissible ambient temperature for the variable-area flowmeters H..../..../M10 with Cat. II3D is
limited to a value of T
Installation and Operating Instruction.
With regard to maximum surface temperatures, variable-area flowmeters are exposed to three heat
sources:
• Ambient temperature T
• Electric power loss P
• Process temperature T
Accordingly, at a given maximum ambient temperature and a given maximum power loss, we obtain
maximum surface temperatures as a factor of the process temperature.
The H..../..../M10 variable-area flowmeter with Cat. II3D in the dust explosion protected version the
categorization T65 correspond to a max. ambient and process temperature of 60°C (140°F). (Max.
surface temperature without dust contamination).
For other ambient and process temperatures use the following formula:
Apart from the based parameters, the measurement part of the device defines at least the max.
surface temperature of the flowmeter.
The permissible max. surface temperature is also defined by the inflammation and glowing
combustion temperature.
Please refer also to EN 50281-1-2, Paragraph 6 (Temperature limitation).
Supplementary Installation and Operating Instructions M10 EEx d
Nominal values of the non-
certified receiver instrument
See Standard Installation
and Operating Instructions
≤ 60V
DC
= -40°C to + 60 °C (-40°F ... +140°F). For restricted values see standard
amb
amb
v
m
T = T + 0,2 (T –T
o amb m
amb
Added restriction
Supply power for receiver
instruments max. 253V
) +5K (T in °C)
amb
= -40°C to +60°C. The nominal
5