Ex-i Relays and Opto-Couplers Definition

Ex-i Relays and Opto-Couplers
Definition:
Often Times electronic equipment is required to carry out certain
functions in potentially explosive atmospheres. To prevent
potential ignition via a spark or arc in these environments, all
components must be selected very carefully. Components
meeting these requirements are generally referred to as
intrinsically safe. This components must be tested such that they
will not become an ignition point when subject to short circuits or
adjacent component failures. They must also switch to a defined
state when subjected to overload conditions.
Components acting as interfaces in the above-defined
application must meet the highest criteria of strict insulation
values and galvanic separation between interconnecting
electrical circuits.
Intrinsically safe Reed Relays are generally used for applications
with low switching frequencies. Standards for these components
are presented in EN500200. Here the required air and creepage
paths as well as the electric strength are defined in detail.
MEDER electronic Inc. 766 Falmouth Rd. Mashpee, MA 02649
Phone 508-539-0002 - Fax: 508-539-4088
www.meder.com
Ex-i Relays and Opto-Couplers
Characteristics:
For voltage specification, a peak voltage of 375 Volts must not
be exceeded in order to meet accepted worldwide standards.
The sum of the input and output voltages must not be higher
than 375 Volts Peak.
• The coil input has a voltage of 24 Volts max. and the
contacts produce 230 VRMS or 325 volts peak output.
Input plus output = 24 + 325 = 349 Volts peak.
Here the safety margin for the voltage for the input and
output meet their peak voltage limit of 375 volts.
• The air path for isolation of this voltage is 6mm and the
creepage path is 10mm.The isolation inside the
component through potting compounds is 2mm.
• Another important value is the Comparative Tracking index
(CTI) value of plastic. In this case, the value must be
greater than 175.
• The electric strength between the input and output is
tested
at 1500 VRMS or 2x the nominal voltage +1000
MEDER electronic Inc. 766 Falmouth Rd. Mashpee, MA 02649
Phone 508-539-0002 - Fax: 508-539-4088
www.meder.com
Ex-i Relays und Opto-Couplers
Certificates:
The certification was issued according to ATEX 94/4 EG by a
German authority, the PTB. The MEDER relays and optocouplers passed the tests successfully and received the
following approval codes:
MRX-Relays:
Opto-Coupler: 522, 542:
525, 535:
567:
PTB
PTB
PTB
PTB
01
01
01
01
ATEX
ATEX
ATEX
ATEX
2050
2043
2049
2042
U
U
U
U
Applications:
Generally, intrinsically safe approved components find
application in the mining industry, chemical processing plants,
refineries, power stations and high dust producing plants. Any
potentially flammable atmospheres represent areas of
applications for these products.
Our MRX series Reed Relays and our 525-03-0-1, 525-04-1,
and 567-70-1-I Opto-coupler series are all ideal for this
environment.
On the upcoming pages you will find an overview of the MRXseries as well as some datasheets of the relays and couplers.
For a special design please contact our nearest sales office or
see our website for more detailed information!
MEDER electronic Inc. 766 Falmouth Rd. Mashpee, MA 02649
Phone 508-539-0002 - Fax: 508-539-4088
www.meder.com