Rockwell Automation Publication 440R-IN081B-EN-P - February 2020
3
Back EMF Monitoring Relay Module
Connect Power Supply
Power for the MSR55P standstill module safety relay depends on the
model. The primary power supply is connected to terminals A1 and A2.
An auxiliary (12…30V DC only) supply voltage can be connected to
terminals A3/A4 to provide semiconductor diagnostics.
Depending on the model, the primary supply can be 24V DC, 115V
AC, or 230V AC. When an AC supply is used, both 50 Hz and 60 Hz
are acceptable.
When powering with 24V DC in the European Union, the DC supply
must have a Protective Extra-Low Voltage (PELV) rating. When
powering with 24V DC in the United States, the DC supply must have
both a PELV rating as well as an NEC Class 2 rating. Many of our
Bulletin 1606 power supplies are PELV and Class 2 compliant.
Power to A1/A2 is required to operate the MSR55P standstill module
safety relay. Power to A3/A4 is only necessary if the solid-state auxiliary
status signals (ON and ERR) are used.
Motor Winding Inputs
The motor windings are connected to terminals L1, L2, and L3. The
connections must be made directly at the motor with no electrical
devices (like transformers and contactors) between the motor and the
shows wiring for a single-phase, DC, and
a three-phase motor.
Figure 2 - Motor Connections
Surge Suppressors
Because of the potentially high current surges that occur when switching
inductive load devices, such as motor starters and solenoids, the use of
surge suppression is required. Adding a suppression device prolongs the
life of the relay outputs and reduces the effects of voltage transients and
electrical noise from radiating into adjacent systems.
Since this is a safety-related system, the surge suppression device must
connected across the load device. The surge suppression device must not
be connected across the MSR55P safety relay contacts.
For outputs that use 24V DC, we recommend 1N4001 (50V reverse
voltage) to 1N4007 (1000V reverse voltage) diodes for surge
suppression. The diode must be connected as close as possible to the
load coil.
For outputs that use 120V AC or 240V AC, we recommend metal oxide
varistors.
Configuration
The configuration of MSR55P safety relays is accomplished by
adjusting the two switches on the front face. Each switch control knob
rotates two potentiometers. The recommended practice is to set the
switches to the minimum setting initially, and then adjust them as
necessary to reduce nuisance tripping while maintaining a safe
application.
V
m
- Monitoring Voltage
The trip voltage of the back EMF is adjusted by the 10-position V
m
potentiometer. When the back EMF drops below the voltage level, the
MSR55P standstill module safety relay begins the delay timer. After the
timer expires, the outputs are de-energized.
each of the catalog numbers.
Table 2 - V
m
- Monitoring Voltage Settings
t
s
- Time Delay
When the back EMF of the motor drops below the V
m
voltage setting,
the standstill delay timer starts. The delay time is set by the 10-position
t
s
potentiometer. During the timing cycle, the OUT indicator flashes.
shows the delay time for each setting. After the delay
expires, the outputs are energized.
IMPORTANT
The three connections create two safety monitor channels. L1
is common to the two channels, which are L2 and L3.
L1 L2
L3
M
K1
K2
A2
X1 X2
1
L
2
L
3
L
X3
34
44
A1
A3
1
1
3
2
3
3
2
1
4
2
ON ERR A4
54
43
53
L1 N
M
K1
K2
A2
X1 X2
1
L
2
L
3
L
X3
34
44
A1
A3
1
1
3
2
3
3
2
1
4
2
ON ERR A4
54
43
53
Single-phase and DC Motor
Three-phase
Position
440R-S35014, 440R-S35015,
440R-S35016 [Volts]
440R-S35011, 440R-S35012,
440R-S35013 [x10mV]
1
0.2
2
2
0.3
3
3
0.4
4
4
0.5
5
5
0.7
7
6
1.0
10
7
1.5
15
8
2
20
9
3
30
10
4
40
