Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
31
Application and Wiring Examples
Chapter 7
E-stop with Contactors
shows a typical application where the MSR55P safety relay monitors
the speed of a motor that contactors turn on and off. When the MSR55P
safety relay detects that the motor has achieved its standstill settings, the
MSR55P safety relay energizes its outputs. You must perform a risk assessment
to determine the proper settings of V
m
and t
s
.
An E-stop push button initiates a safety stop. A PLC turns the motor on and
off, provided the safety system is enabled.
The SI safety relay monitors the contactors K1 and K2, the MSR55P through
its contacts 11/12, and the E-Stop. The SI is set for monitored manual reset to
prevent the motor from restarting when the e-stop button is released. The
status of the SI relay (terminal Y32) must be monitored by the PLC. The PLC
must turn OFF its outputs when the E-stop is pressed.
Figure 17 - E-stop with Motor Controlled by Contactors
Table 8 - E-stop with Contactors
Application
Description
Safety Enable
Release the E-stop and press the Reset button.
Production Start/Stop
With the safety system enabled, the PLC can start and stop the motor.
Safety Stop
Press the E-stop to stop the motor; the motor coasts to a stop. When the motor spins down to a speed below the V
m
setting of 70 mV, the MSR55P
safety relay begins its timing sequence. After 3 seconds, the MSR55P safety relay energizes its outputs.
Safety Rating
The safety system has two functions (E-stop and speed monitoring). Both functions can be used in applications up to Category 4, PLe per ISO13849-1
and SIL CL 3 per IEC 60261. The speed monitoring rating of the system depends on how the outputs of the MSR55P safety relay are used.
This application has two safety functions:
1. Enable safety devices only when the motor is stationary. This safety function meets Cat 4, PLe, SIL 3 due to the rating of the MSR55P.
2. Initiate a coast to stop by pressing the E-stop button. This safety function is limited to Cat 4, PLe, SIL 3 due to the rating of the SI relay, the
redundancy, of the e-stop contacts, and the redundancy and monitoring of the contactors.
MSR55P
440R-S35011
L1 L2
L3
M
K1
K2
3~
24V DC Com
E-Stop
800FM-MT64MX02S
Reset
800FM-
F611MX10
Safety Devices
ON Status
Error Status
100S Contactors
+24V DC
K1 K2
PLC
Inputs
Start
Stop
Outputs
A1
S11 S21
S12
S22
L11
Y32
13
14
23
24
S34
A2
SI
440R-S12R2
RESET
0
MM
AM
A2
X1
X2
L3
L2
L1
X3
34
44
A1
A3
33
23
11
24
12
ON ERR A4
54
43
53
ON Status
.2 .3 .5.7
1
1.5
6
3
4
2
ts
2 3 4 5
7
10
20
30
40
15
Vm
x10mV
