Product Specifications; Function - Pepperl+Fuchs MFT Series Manual

Multifunction Terminal MFT-***.****(.L)

Product Specifications

2 Product Specifications
2.1

Function

Many applications in hazardous areas work with field devices that do not have
intrinsically safe connections. In these applications, protection methods such as type Ex e
protection (increased safety) are used. In contrast to intrinsically safe circuits,
increased safety connections are generally not accessible when energized. Disconnecting
these circuits for maintenance would therefore require either the plant to be shut down
or a hot work permit to be obtained.
The multifunction terminal offers the following options for disconnecting
non-intrinsically safe circuits or removing plug-in modules in hazardous areas:
• The multifunction terminals MFT-R.****, MFT-2R.****, MFT-D****(.L), MFT-2D.****,
MFT-F.****(.L), MFT-2F.****, MFT-2L.**** enable the non-intrinsically safe circuits
to be disconnected.
• The multifunction terminals MFT-FT.****, MFT-RNO.****, MFT-RNC.**** enable
the plug-in modules to be removed even in hazardous areas.
The non-intrinsically safe circuits are separated in 2 steps:
• Step 1
The electrical contacts between the base module and the plug-in module are separated
in areas protected by the type of protection Ex d.
In this position the sparks, that have formed within the contact area, can no longer ignite
the possibly existing surrounding atmosphere.
• Step 2
The plug-in module, which is now completely electrically isolated, can now be removed.
Possible ignition sources in the area of the electrical contacts are no longer present.
The electrical connections of the base module are protected and comply with degree
of protection IP30 according to IEC/EN 60529. After removal, the plug-in module
is de-energized.
• Once the plug-in module has been removed, the de-energized side is accessible.
This allows field devices that are connected to the de-energized side to be replaced,
while the remaining part of the system continues to be energized.
Typical applications for the multifunction terminal are:
• Fusing Ex d valves, signal lamps, acoustic sensors
• Diode decoupling of supply circuits
• Simple OR gate for Zone 1 mounting
• Visible disconnect of field devices
• Relay switch for power circuits
• Current limitation using resistors
• Optocoupler applications
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