INM 5500 Rev 11
20
6.1.3 MTL5501-SR - Fail-safe Switch/Proximity detector interface
Single channel, fail-safe module with line-fault detection
The MTL5501-SR enables a fail-safe switch/proximity detector located in the hazardous area
to control an isolated fail-safe electronic output. It provides line-fault detection (LFD) alarm
contacts and is designed for use with approved fail-safe sensors in loops that require operation
up to SIL3 according to the functional safety standard IEC 61508.
Note: For reliable, long-term operation the load on the LFD switching relay should be not less
than 50mW, e.g. 10mA at 5V DC.
Hazardous area Safe area
Vs–
Vs+
20 to 35V dc
10kΩ
1k4Ω
+
–
LFD
output
+
–
Resistors must
always be fitted
for switch inputs
6
5
4
3
2
1
7
8
9
10
11
12
13
14
Terminal Function
1 Input –ve
2 Input +ve
7 Output –ve
8 Output +ve
10 LFD
11 LFD
13 Supply –ve
14 Supply +ve
Figure 6.2:
Top label for
MTL5501-SR
Input / output characteristics
Input value in
sensor circuits
Fail–safe
output
Operation LFD
contacts
2.9mA < Is < 3.9mA ON Normal CLOSED
Is < 1.9mA & Is > 5.1mA OFF Normal CLOSED
Is < 50µA OFF Broken line OPEN
Rs < 100Ω OFF Shorted line OPEN
Correct operation of the fail-safe output and LFD is indicated by the LEDs on the front of the
unit. The yellow O/P LED is ON when the fail-safe output is energised. The red LFD LED flashes
if a line fault is detected. The fail-safe output is de-energised (OFF) if the module detects an
incorrect sensor current, an open circuit or a short circuit in the sensor circuit.
Input signal sensors may be either suitable proximity sensors or switches. The proximity sensor
properties are specified in the standard EN60947-5-6:2001; however, when used with
MTL5501-SR modules, additional requirements for the “low-impedance” current of 3.4
±0.5mA must be met. The list below shows suitable proximity sensors, all manufactured by
Pepperl+Fuchs Group, Germany, and specified as usable to SIL3, according to IEC 61508:
SJ 2-SN NJ 4-12GK-SN NJ 10-30GK-SN
SJ 3,5-SN NJ 5-18GK-SN NJ 15-30GK-SN
SJ 3,5 -S1N NJ 8-18GK-SN NJ 6 S1+U1+N
NJ 2-11-SN NJ 6-22-SN NJ 15S+U1+N
NJ 2-11-SN - G NJ 6-22-SN-G NJ 20S+U1+N
NJ 2-12GK-SN NJ 5-30GK-S1N NJ 40-FP-SN-P1
To Next Page
Loading...
Need help?
General
