Digital Input Modules; Phase Reversal; Line-Fault Detection (Lfd) - Eaton Crouse-Hinds Series Instruction Manual

INM 4500/4600 Rev 12
DRAFT - 22 March 2018
6 .1

Digital Input modules

The Digital Input (DI) module range offers solid state or relay output switches in a safe area
that respond to input switches located in a hazardous area. Single or multiple channel (2 or
4) options are available, as well as Line-Fault Detection (LFD).
Modules with LFD can recognise open or short circuit conditions on the input wires going to
the field sensors, and some DI modules have the facility to reverse the effect of the input
on the output i.e. phase reversal.
These options are chosen with switches located on the edge of the module on the
hazardous area terminal side. In some applications it may be easier to set these switches
before fitting the module to the backplane.
Figure 6 .1:
Switches
to set LFD and

phase reversal

PR = phase reversal
LF = line fault
6 .1 .1 Phase reversal
Set the PR switch ON or OFF for the appropriate channel(s).
6 .1 .2

Line-Fault Detection (LFD)

Where fitted, set the LF switch ON or OFF for the appropriate channel(s). Note: LFD is
permanently active on the MTL4501-SR.
For all DI modules with LFD except for the MTL4501-SR; when using the LFD facility with a
contact input, resistors must be used. Fit 500 to 1k (preferred value 680 ) in series with the
switch and 20k to 25k (preferred value 22k ) in parallel with the switch.
For modes of operation of the MTL4510 & MTL4510B that include LFD, resistors should be fitted
as described above.
For MTL4501-SR use 1k4 in series and 10k in parallel with switch contact inputs.
For hazardous-area inputs conforming to EN 60947-5-6:2001 (NAMUR), a line fault is judged by
the following rules:
• Open circuit condition if hazardous-area current <50µA
• Line integrity (no open circuit) if hazardous-area current >250µA
• Short circuit condition if hazardous-area load <100
• Line integrity (no short circuit) if hazardous-area load >360
Note: the open circuit window (between 250µA and 50µA), and the short circuit window (between
100 and 360 ), is not hysteresis. All MTL4500 range of modules, with inputs conforming to
EN 60947-5-6:2001 (NAMUR), will switch between open and complete circuit conditions within
these limits.
The MTL4501-SR, MTL4514N and the MTL4504 LFD relays de-energise when a fault condition
is detected. The MTL4514 and the MTL4517 energise the LFD relay to indicate a fault condition.
1 2 3 4
OFF position
MTL4513, MTL4516
CH1 CH2
MTL4516C & MTL4517
PR LF PR LF
MTL4511,MTL4514 &
MTL4514N
ON position
- Ch 1 & 2
MTL4504
- Ch 1 only
15