Atex Considerations; Purging - Siemens LDS 6 Operating Instructions Manual

Installation guidelines

4.5 Purging

4.4

ATEX considerations

A hybrid cable is used to connect the transmitter optics housing to the barrier.
Connecting transmitter optics housing to barrier
1. Cut off the pre-mounted phoenix contacts on both sides of the hybrid cable.
2. Insert the hybrid cables (one for each channel) in the feed through at the top of the barrier
box. Fasten each cable with a gasket.
3. Connect each hybrid cable to the Surge Protection Devices SD32X (yellow). - (brown cable)
shall be connected to inlet number 4 and + (green cable) to inlet number 5.
4. Connect the hybrid cable to the transmitter optics housing.
Connecting receiver to transmitter optics housing
For ATEX versions of the LDS 6 the optics housing are premounted with special ATEX electronics
and surge protection. The green phoenix contact mounted on the sensor card is already
connected with a red wire for +24 V and a black wire for GND. Two additional wires should be
connected to the phoenix connector. These wires come from the sensor connection cable.
1. Connect the green wire next to the red one (for 24 V) on the phoenix contact.
2. Connect the brown wire next to the black one (for GND) on the phoenix contact.
Connect the optics housings, on both the transmitter and the receiver side, to earth using the
premounted 2 meters earth cable (yellow-green). AD_4100-2080_Transmitter_Ex_Std_CD6
and AD_4100-2081_Receiver_Ex_Std_CD6 in Appendix A shows the transmitter and receiver
optics housings. All ATEX devices are labelled.
See also
ATEX setup (Page 45)
4.5 Purging
Protecting the optical surfaces
In many applications the wedge windows are exposed to very rough environments and will get
stained very quickly if no measures are taken. Three existing methods to keep the wedge
windows in good shape are:
• Instrument air purging
• Purging with air blower
• Steam purging
These methods are further described in Appendix.
Purging can be divided into purging of optical process interface and purging of optics housings.
26
LDS 6, Optics Housing CD 6
Operating Instructions, 01/2022, A5E01134377-05