Oldham MX 52, Commissioning, Operating And Maintenance Manual

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Oxygen detectors:
- European Standard EN 50104 where the device is used with OLCT 20, 40, 50 and 60 gas
detectors. Where the device is used with other types of sensor producing an output
measurement current of 4/20 mA, they must comply with paragraph 1.5 of Appendix II
of the ATEX 94/9/EC Directive and be compatible with their characteristics (cf. device
transfer curve).
- European Standard EN 50271
9.3. Connecting detectors other than OLDHAM detectors to the MX52
device
As previously explained, users wishing to connect detectors other than those manufactured by
OLDHAM, must ensure their compatibility with the device in order that the resulting combination
may be considered as a safety device.
9.3.1. Device transfer curves in 0% to 100% LEL configuration
The following curve shows the response of the device in terms of value measured, and fault
processing as a function of the input current value supplied by the detector. Where the user connects
a brand of detector other than OLDHAM to the MX52 device, he must check carefully that the
transfer curve is fully compatible with the device input characteristics, to ensure that the data
generated by the detector is correctly interpreted. Equally, the device must supply a suitable power
supply voltage, allowing for cable voltage losses.
Please note:
When the value measured is >= 100% LEL, the measuring device memorises the fact
that the value has exceeded the scale and the channels switch to alarm and fault mode. Resetting
these statuses is a manual operation to be performed by the user, who must follow the safety
regulations specific to the site. The reset is checked either by turning the device on and off or by a
maintenance inspection.
4
mA 20
mA
100% LEL
Signal supplied by
the detector in mA
Display
in % LEL
Fault
Fault
1.2
mA
0% LEL
-17.5% LEL
SUP