Testing Principles And Safety Information For Ex-I - Honeywell Fema DCM-203-574 Series Assembly And Operating Instructions Manual

6. Testing Principles and Safety Information for Ex-i, valid for Ch. 6.1 and 7
6. Testing Principles and
Safety Information for Ex-i,
valid for Ch. 6.1 and 7
According to: EN60079-11
Ex-i intrinsic safety is based upon the
principle that devices in systems equipped
with an ATEX-certified switching amplifier
require only minimal voltage and current.
Sparks which might form when the micro-
switch's contact is opened are thus mini-
mized, as a result of which the surrounding
flammable atmosphere cannot be ignited.
FEMA Ex-i pressure switches are
equipped with gold contact microswitches
(except for those devices featuring internal
interlocking for the purpose of min. or max.
limitation). A blue cable gland, the Ex-I
manufacturer's plate, and the serial
number identify those pressure switches
suitable for use in intrinsically safe circuits.
Generally speaking, Ex-I pressure
switches are suitable for use in zones 1
and 2 (gas) as well as 21 and 22 (dust).
MU2B-0238GE51 R0616D
When equipped with a category "ia"
switching amplifier, such devices can also
be employed on the process-side in zone
20 (dust) and zone 0 (gas).
Devices not equipped with line- and short-
circuiting monitoring:
DCM, DDCM, DNM, DNS, VCM, VNM,
VNS, ending with -513 or -563.
E.g.: DCM6-513, pressure switch 0.5 to 6 bar, conforming
to Ex-i, with gold contact.
Devices equipped with line- and short-
circuiting monitoring:
DCM, DDCM, DNM, DNS, VCM, VNM,
VNS, ending with -574, -575, -576, -577.
E.g.: DCM6-576, pressure switch for max. pressure
monitoring for max. pressure monitoring, 0.5 to 6 bar,
conforming to Ex-I, with line-monitoring.
Regardless of the device's certification and
irrespective of the microswitch, these
devices are also equipped with an
additional resistor-combination (10kΩ /
1.5kΩ) which – in combination with a
suitable (ATEX-certified) switching
amplifier – is suitable for monitoring the
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