The Allen-Bradley Guardmaster® MSR55P back EMF modules are
suitable to monitor the standstill of all electric motors that generate a
remanence voltage while coasting to stop.
The MSR55P standstill module is connected to the motor terminals
and measures the induced back EMF voltage. Two redundant measuring
channels are used (L2-L1 and L3-L1). If the back EMF voltage drops to
0V simultaneously in both channels, it indicates standstill and the
output relay is energized.
The voltage threshold that indicates a standstill on the MSR55P
module is adjustable. This standstill allows the unit to work with
different types of motors in various applications. The standstill time T
(time delay between detection and energizing of the relay) is also
adjustable.
The MSR55P standstill module detects a broken wire on the measuring
inputs L1/L2/L3. If a broken wire is detected, the relay outputs go into
safe state (as with running motor).
Features
• Safe standstill detection on three-phase and single-phase motors
• Performance Level is PLe
• Category 4 to EN ISO13849-1: 2008
• SIL Claimed Level (SIL CL) 3 to IEC/EN 62061
• Safety integrity level (SIL) 3 to IEC/EN 61508 and IEC/
EN61511
• No external sensors necessary
• Standstill detection independent of direction
• Broken wire detection
• Three N.O. contacts, one N.C. contact for up to AC 250V
• Two semiconductor monitored outputs
• One monitored output (N.O. contact)
• Adjustable voltage setting
• Adjustable standstill time delay
• LED indicators for standstill, event of line breakage and
operation voltage
• Suitable for operation with inverters
• Removable screw terminals
Figure 1 - Overview of Key Features
DIN Rail Mounting and Removal
s
MSR55P standstill module safety relays mount onto 35 mm DIN rails.
Spacing
MSR55P standstill module safety relays can be mounted directly next to
other MSR and GSR safety relays.
Maintain a space of 50.8 mm (2 in.) above, below, and in front of the
relay for adequate ventilation.
Removable Terminals
MSR55P standstill module safety relays have removable terminals to
ease wiring and replacement.
1. Insert the tip of a small
screwdriver into the
slot near the terminal
screws.
2. To unlock the terminal
block, rotate the
screwdriver.
Page 2
Back EMF Monitoring Relay Module
3534113233
4544214243
3534113233
4544214243
Excessive Heat Prevention
For most applications, normal convective cooling keeps the relay within
the specified operating range. Verify that the specified temperature
range is maintained. Usually, proper spacing of components within an
enclosure is sufficient for heat dissipation.
Additional provisions are necessary to cool equipment when high
ambient temperatures are encountered. Do not bring in unfiltered
outside air. Place the MSR55P standstill module in an enclosure in order
to help protect it from a corrosive atmosphere. Harmful contaminants
or dirt could damage components or cause improper operation. In
extreme cases, air conditioning helps protect against heat buildup
within the enclosure.
Wiring Requirements and Recommendation
ATT EN TI ON : Before you install and wire any device, disconnect
power to the system.
Calculate the maximum possible current in each power and
common wire. Observe all electrical codes that dictate the
maximum current allowable for each wire size. Current above the
maximum rating causes wiring to overheat, which can cause
damage.
Figure 2 - Relay Face and Terminal Identification
53 54 L1 L2 L3
X1 X2 X3 11 23 33 43
PWR
.3
.2 .4
4
3
.3
.2 .4
6
4
.5
.7
1
1.5
23
.5
.7
1
1.5
2
3
V
OUT
ERR
12 24 34 44
A3 A4 ON ERR A1 A2
MSR55P
m
t
s
53 54 L1 L2 L3
X1 X2 X3 11 23 33 43
PWR
3
OUT
24
ERR
12 24 34 44
A3 A4 ON ERR A1 A2
40
.2 .5
6
15
0302
.3
2
4
3
x10mV
5
7
10
.7
1
1.5
t
MSR55P
m
s
• Allow for at least 50 mm (2 in.) between I/O wire ducts or
terminal strips and the relay.
• Route incoming power to the relay by a path separate from the
device wiring. Where paths must cross, their intersection must
be perpendicular.
• Do not run signal or communications wiring and power wiring
in the same conduit. Route wires with different signal
characteristics by separate paths.
• Separate wiring by signal type. Bundle wiring with similar
electrical characteristics together.
• Separate input wiring from output wiring.
• Label wiring to all devices in the system. Use tape, shrinktubing, or other more dependable means to label wire. Use
colored insulation as well to identify wiring by signal
characteristics. For example, use blue for DC wiring and red for
AC wiring.
ATT EN TI ON : The outputs 53…54, ON and ERR are only
monitoring outputs and must not be used in safety circuits.
Voltage-free redundant safety contacts (N.O.)
are ON.
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.
2Rockwell Automation Publication 440R-IN081A-EN-P - June 2019
Page 3
Back EMF Monitoring Relay Module
L1
L2 L3
M
K1
K2
A2
X1
X2
1L2L3L
X3
34 44
A1A3113233
2142ON
ERR
A454
43 53
Three-phase
L1
N
M
K1
K2
A2
X1
X2
1L2L3L
X3
34 44
A1A3113233
2142ON
ERR
A454
43 53
Single-phase and DC Motor
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 a 24V DC supply is used, it must comply with the CE
(European) Low Voltage Directive (LVD) or the U.S. National Electric
Code. In the European Union, the 24V DC supply must be a safety extra
low voltage (SELV) or protected extra low voltage (PELV) rated supply.
In the U.S., a PELV or Class 2 supply must be used. Many of the Bulletin
1606 power supplies are SELV-, 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
MSR55P safety relay. Figure 3
a three-phase motor.
IMPORTANTThe three connections create two safety monitor channels. L1
is common to the two channels, which are L2 and L3.
Figure 3 - Motor Connections
shows wiring for a single-phase, DC, and
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.
Vm - Monitoring Voltage
The trip voltage of the back EMF is adjusted by the 10-position V
potentiometer. When the back EMF drops below the voltage level, the
MSR55P standstill module safety relay begins the delay timer. After the
voltage exceeds that voltage setting, the outputs are de-energized.
shows the settings of each of the catalog numbers.
Ta b l e 2
Table 2 - V
Positio n
- Monitoring Voltage Settings
m
440R-S35014, 440R-S35015,
440R-S35016 [Volts]
10.22
20.33
30.44
40.55
50.77
61.010
71.515
8220
9330
10440
440R-S35011, 440R-S35012,
440R-S35013 [x10mV]
m
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 helps protect and extend the operating life of the
relays. By adding a suppression device directly across the coil of an
inductive device, you can prolong the life of the outputs. You also reduce
the effects of voltage transients and electrical noise from radiating into
adjacent systems.
t
- Time Delay
s
When the back EMF of the motor drops below the Vm voltage setting,
the standstill delay timer starts. The delay time is set by the 10-position
potentiometer. During the timing cycle, the OUT indicator flashes.
t
s
Tab le 3 on pa g e 4
shows the delay time for each setting. After the delay
expires, the outputs are energized.
Rockwell Automation Publication 440R-IN081A-EN-P - June 20193
Page 4
Rockwell Otomasyon Ticaret A.Ş., Kar Plaza İş Merkezi E Blok Kat:6 34752 İçerenköy, İstanbul, Tel: +90 (216) 5698400
Flashing codes of the ERR indicator in sequence of priority
2) Wire-break/oset on L1 or L2
3) Wire-break/oset on L3
5) Simultaneity failure signal L2/L3
6) Potentiometer error V
7) Potentiometer error t
PositionDelay Time [seconds]
10.2
20.3
30.5
40.7
51.0
61.5
72.0
83.0
94.0
106.0
Status Indicators and Diagnostics
Three indicators on the front provide the operating status of the
MSR55P standstill module safety relay. Ta b l e 4 describes the state of
each indicator.
Table 4 - Stat us In dicato rs
IndicatorStateDescription
OffNo power to A1
PWR
OUT
ERR
MSR55P standstill module safety relays include a number of facilities to
detect faults that could influence the safety function of the module.
Checks are conducted on power- up of the unit and in cycles during
normal operation. If a fault occurs, the output relays switch off. The
fault state is indicated with the ERR indicator, the PWR
the semiconductor output ERR.
GreenNormal operation
RedInternal Fault
GreenSafety outputs are energized
Flashing greenIn timing cycle
Flashing orangeIntermittent crossing of the V
OrangeSafety outputs are de-energized
OffCode 1 or code 5 error is present
OffNo faults exist; normal operation
Flashing red
Fault is present. See (ERR Flashing Codes in User
Manual, 440R-UM014.
indicator, and
trip point
m
With safety relevant failures, your MSR55P standstill module safety
relay differentiates between external failures (broken wire/offset,
simultaneity failure, or feedback circuit failure) and internal failures.
Broken wire/offset failures and feedback circuit failures can be restored
by using manual reset. They can also be reset automatically after
removing the fault by placing a jumper from terminal X2 toX3.
The number of times the ERR status indicator blinks communicates
diagnostics. When multiple faults exist simultaneously, the ERR
indicator shows the highest priority. After the highest priority fault is
corrected, the ERR shows the next highest priority fault.
Figure 4 - ERR Flashing Codes
Waste Electrical and Electronic Equipment (WEEE)
At the end of life, this equipment should be collected separately
from any unsorted municipal waste.
Rockwell Automation maintains current product environmental information on its webs ite at http://www.rockwellautomation.com/rockwellautomation/about-us/sustainability-ethics/product-environmental-compliance.page.
Allen-Bradley, Guardmaster, Rockwell Automation, and Rockwell Software are trademarks of Rockwell Automation, Inc.
Trademarks not belonging to Rockwell Automation are property of their respec tive companies.
Publication 440R-IN081A-EN-P - June 201910005051946 Ver 00