Rockwell Automation Allen-Bradley GuardMaster MSR55P Back EMF... User manual

MSR55P Back EMF Minotaur Safety Relay
Catalog Numbers 440R-S35011, 440R-S35012, 440R-S35013, 440R-S35014, 440R-S35015, 440R-S35016
User Manual
Original Instructions

Important User Information
Read this document and the documents listed in the additional resources section about installation, configuration, and
operation of this equipment before you install, configure, operate, or maintain this product. Users are required to
familiarize themselves with installation and wiring instructions in addition to requirements of all applicable codes, laws,
and standards.
Activities including installation, adjustments, putting into service, use, assembly, disassembly, and maintenance are
required to be carried out by suitably trained personnel in accordance with applicable code of practice.
If this equipment is used in a manner not specified by the manufacturer, the protection provided by the equipment may
be impaired.
In no event will Rockwell Automation, Inc. be responsible or liable for indirect or consequential damages resulting from
the use or application of this equipment.
The examples and diagrams in this manual are included solely for illustrative purposes. Because of the many variables and
requirements associated with any particular installation, Rockwell Automation, Inc. cannot assume responsibility or
liability for actual use based on the examples and diagrams.
No patent liability is assumed by Rockwell Automation, Inc. with respect to use of information, circuits, equipment, or
software described in this manual.
Reproduction of the contents of this manual, in whole or in part, without written permission of Rockwell Automation,
Inc., is prohibited
Throughout this manual, when necessary, we use notes to make you aware of safety considerations.
Labels may also be on or inside the equipment to provide specific precautions.
WARNING: Identifies information about practices or circumstances that can cause an explosion in a hazardous
environment, which may lead to personal injury or death, property damage, or economic loss.
ATTENTION: Identifies information about practices or circumstances that can lead to personal injury or death, property
damage, or economic loss. Attentions help you identify a hazard, avoid a hazard, and recognize the consequence.
IMPORTANT Identifies information that is critical for successful application and understanding of the product.
SHOCK HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that dangerous
voltage may be present.
BURN HAZARD: Labels may be on or inside the equipment, for example, a drive or motor, to alert people that surfaces may
reach dangerous temperatures.
ARC FLASH HAZARD: Labels may be on or inside the equipment, for example, a motor control center, to alert people to
potential Arc Flash. Arc Flash will cause severe injury or death.Wear proper Personal Protective Equipment (PPE). Follow ALL
Regulatory requirements for safe work practices and for Personal Protective Equipment (PPE).

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 3
Table of Contents
Important User Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Table of Contents Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Who Should Use This Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Summary of Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Additional Resources . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Chapter 1
Overview Safety Relay Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Chapter 2
Installation Mounting Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
DIN Rail Mounting and Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Removable Terminals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Spring Clamp Terminals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Enclosure Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Prevent Excessive Heat . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Chapter 3
Power, Ground, and Wire Wiring Requirements and Recommendation . . . . . . . . . . . . . . . . . . . . 13
Wire Size and Terminal Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Terminal Assignment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Connect Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Motor Winding Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Safety Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Derating Curve. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Surge Suppressors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
Auxiliary Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Monitoring Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Fault Reset Input. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Chapter 4
Configuration Vm - Monitoring Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
ts - Time Delay. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Chapter 5
Timing Diagram Timing Diagram Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Chapter 6
Status Indicators and Diagnostics ERR Flashing Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Line Breakage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
With Motor at Standstill. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

4Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Table of Contents
With Motor Spinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Simultaneity of Measuring Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Potentiometer Error. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Internal Device Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Chapter 7
Application and Wiring Examples Guard Locking and E-stop with Electronic Drive . . . . . . . . . . . . . . . . 29
E-stop with Contactors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
Wye-Delta Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
Chapter 8
Troubleshooting Tools Needed. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Required Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Follow These Steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
View PWR Indicator (Step 1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
ERR Indicator Flashes One Time (Step 2). . . . . . . . . . . . . . . . . . . . . . . 36
Wire Break at L1, L2, or L3 (Step 3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
Feedback Circuit Open (Step 4) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
ERR Indicator Flashes 5 Times (Step 5) . . . . . . . . . . . . . . . . . . . . . . . . . 38
ERR Flashes 6 or 7 Times (Step 6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Output Is Energized but Contactors Are Off (Step 7) . . . . . . . . . . . . 39
Output Is On While Motor Still Turns (Step 8) . . . . . . . . . . . . . . . . . 39
Appendix A
Specifications General. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Environmental . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Power Supply (A1/A2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Inputs (L1/L2/L3) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Safety Outputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Status Outputs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
Appendix B
Regulatory Approval Agency Certification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Compliance to European Union Directives. . . . . . . . . . . . . . . . . . . . . . 43
EMC Directive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
Machine Safety Directive. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
SIL Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Performance Level/Category . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 5
Preface
This manual is a reference guide for MSR safety relays. It describes the
procedures that you use to install, wire, and troubleshoot your relay. This
manual explains how to install and wire your relay and gives an overview of the
operation of the MSR safety relays
Who Should Use This Manual Use this manual if you are responsible for designing, installing, programming,
or troubleshooting control systems that use the MSR safety relays.
You must have a basic understanding of electrical circuitry and familiarity with
safety-related control systems. If you do not, obtain the proper training before
using this product.
Summary of Changes This publication contains new and updated information as indicated in the
following table.
Definitions The following terms and abbreviations are used throughout this manual. For
definitions of terms that are not listed here, refer to the Allen-Bradley
Industrial Automation Glossary, publication AG-7.1.
•N.C. (Normally Closed) - An electrical contact whose normal state
(that is, no pressure or electrical potential applied) is in the closed
position.
•N.O. (Normally Open) - An electrical contact whose normal state (that
is, no pressure or electrical potential applied) is in the open position.
•PLC - A programmable logic controller or a programmable automation
controller.
•Response Time - Describes the time between the trigger of one input to
the OFF state of the output. Throughout this manual, the safety outputs
can be described as turning off immediately, which means that the safety
outputs turn off within the response time.
Topic Page
UpdatedTypical Applications in Table 2 8
Updated Enclosure Considerations section 10
Updated Surge Suppressors section 17
Updated Figure 12 19
Updated Guard Locking and E-stop with Electronic Drive section 29
Updated E-stop with Contactors section 31
Updated Figure 18 32
Updated Table 11 41
Updated Table 12 42
Updated Regulatory Approvals 43, 44

6Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Preface
•OSSD (Output Signal Switching Device) - Typically a pair of solid-
state signals that are pulled up to the DC source supply. The signals are
tested for short circuits to the DC power supply, short circuits to the
DC common and shorts circuits between the two signals.
•Outputs Energized/De-energized - Table 1 describes that state of the
outputs in this manual when the output is described as energized or
de-energized.
The exception is the semiconductor output ERR, which is not described
in Tab le 1. The ERR semiconductor output is ON when an error is
detected and OFF when no error is detected.
Table 1 - State of the Outputs
Additional Resources These documents contain additional information concerning related products
from Rockwell Automation.
You can view or download publications at rok.auto/literature.
Terminal De-energized Energized Type Function
11/12 Closed Open
Voltage free
Monitoring
(non-safety)
23/24 Open Closed
Safety related33/34 Open Closed
43/44 Open Closed
53/54 Open Closed Status only
ON Off On Semi-conductor
Resource Description
Industrial AutomationWiring and Grounding Guidelines,
publication 1770-4.1 Provides general guidelines for installing a
Rockwell Automation® industrial system.
Product Certifications website: rok.auto/certifications Provides declarations of conformity, certificates, and
other certification details.

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 7
Chapter 1
Overview
Safety Relay Features Figure 1 - Overview of Key Features
MSR55P back electro-motive-force (EMF) safety relays monitor the voltage
that motors generate after their drive voltage is removed and the motor coasts
or brakes to a stop. MSR55P safety relays monitor either single- or three-phase
motors. MSR55P safety relays operate with pulse width modulated (PWM)
drives, smart motor controllers, and electromechanical contactors.
MSR55P safety relays are connected to the motor terminals and measure the
induced back EMF as the motor spins to a stop. MSR55P safety relays create a
two-channel system by measuring the voltage from L2 to L1 and the voltage
from L3 to L1. If the back EMF voltage drops to a certain threshold
simultaneously in both channels for a certain duration, standstill is considered
achieved, and the outputs are energized.
If the voltage measured on terminals L1/L2/L3 of the MSR55P safety relay
rises over the adjusted value plus hysteresis in at least one channel (the motor is
switched on or the shaft turns mechanically), the forcibly guided output
contacts are switched off immediately (contacts 23/24, 33/34 and 43/44 open
while contact 11/12 closes). The monitoring relay de-energizes (53/54
opened), the semiconductor output ON goes off and the OUT indicator turns
yellow (= Vm over adjusted value).
To accommodate many types of motors, you can make two adjustments in
accordance with the machine risk assessment:
• The threshold of the back EMF voltage.
• A time delay to add additional assurance that the motor has stopped.
Removable terminal blocks
Standstill voltage setting
Standstill time delay setting
Three indicators for status
and diagnostics

8Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 1 Overview
MSR55P safety relays can monitor external safety relays and contactors. By
monitoring the normally closed contacts, MSR55P safety relays help prevent
re-energization of its outputs if the safety relays or contactors have not de-
energized. If feedback monitoring is not required, the monitoring circuit must
be jumpered.
MSR55P safety relays perform internal tests on startup and during operation.
Some faults are reset automatically when the fault is cleared. Other faults are
reset manually, by a manually operated switch, or automatically by a jumper.
See Status Indicators and Diagnostics on page 25 and Troubleshooting on
page 33 for further details.
Table 2 lists the six catalog numbers that are available. The key differences are
the power supply to terminals A1/A2 and the setpoint voltage to determine
safe standstill speed as the motor spins to a stop.
In general, select models that have the lower standstill monitoring voltage
when induction motors are monitored. Servo motors, which have permanent
magnets, generally create high voltages at slower revolutions, therefore, the
higher standstill monitoring voltage is usually the preferred solution. You must
evaluate your application and apply the risk assessment process to determine
the proper relay for their specific application.
Table 2 - Model Selection
A1/A2 Supply Voltage
Standstill Monitoring
Voltage Range Typical Applications Cat. No.
24V DC 20…400 mV
Induction motors with
contactors
440R-S35011
115V AC 20…400 mV 440R-S35012
230V AC 20…400 mV 440R-S35013
24V DC 200 mV…4V Induction and servo
(permanent magnet)
motors with variable
frequency and servo drives
440R-S35014
115V AC 200 mV…4V 440R-S35015
230V AC 200 mV…4V 440R-S35016

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 9
Chapter 2
Installation
Mounting Dimensions MSR55P safety relays come standard with removable screw-type terminals.
Spring-clamp terminals are offered as an option. Figure 2 shows the mounting
dimensions.
Figure 2 - Dimensions [mm (in.)]
DIN Rail Mounting and
Removal
MSR55P safety relays mount onto 35 mm (1.4 in.) DIN rails:
35x7.5x1 mm(1.4x0.3x0.03 in.) — EN50022 - 5x7.5.
1. Hold the top at an angle (Figure 3).
2. Slide down until the housing catches the rail.
3. Swing the bottom down and push until the latch clips onto the rail.
Figure 3 - DIN Rail Mounting
45 (1.8)
35
(1.4)
121 (4.8)
90
(3.5)
113 (4.4)
104 (4.1)
Screw Terminals
111 (4.4)
Spring-clamp
Terminals
DIN Rail Latch DIN
Rail

10 Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 2 Installation
Removal
To remove the MSR55P safety relay, use a screwdriver to pry the DIN rail latch
downwards until it is in the unlatched position. Then, swing the module up.
Spacing
MSR55P 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 safety relays have removable terminals to ease wiring and
replacement.
Figure 4 - Removable Terminals
1. Insert the tip of a small screwdriver into the slot near the terminal
screws.
2. To unlock the terminal block, rotate the screwdriver.
The terminal block can then be removed from the housing.
Spring Clamp Terminals As an accessory, you can purchase removable terminals with spring clamps. The
spring clamp terminals can directly replace the screw clamp terminals. See
Table 10 on page 41 for the differences in wire size.
Enclosure Considerations Most applications require installation in an industrial enclosure to reduce the
effects of electrical interference and environmental exposure. Pollution
Degree2 is an environment where normally only non-conductive pollution
occurs except that occasionally temporary conductivity from condensation can
be expected. Overvoltage Category II is the load level section of the electrical
distribution system. At this level, transient voltages are controlled and do not
exceed the impulse voltage capability of the product insulation.
M4105_a

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 11
Installation Chapter 2
This equipment is intended for use in a Pollution Degree 2 industrial
environment, in overvoltage Category II applications (as defined in IEC
60664-1), at altitudes up to 2000 m (6562 ft) without derating. This
equipment is considered Group 1, Class A industrial equipment according to
IEC/CISPR 11. Without appropriate precautions, there can be difficulties
with electromagnetic compatibility in residential and other environments due
to conducted and radiated disturbances.
This equipment is supplied as open-type equipment. The relays must be
mounted within an enclosure that is suitably designed for those specific
environmental conditions that are present and appropriately designed to help
prevent personal injury as a result of accessibility to live parts. The interior of
the enclosure must be accessible only by the use of a tool. Subsequent sections
of this publication contain additional information regarding specific enclosure-
type ratings that are required to comply with certain product safety
certifications.
For more information, see:
• Industrial Automation Wiring and Grounding Guidelines, publication
1770-4.1, for additional installation requirements.
• NEMA Standard 250 and IEC 60529, as applicable, for explanations of
the degrees of protection provided by different types of enclosure.
Prevent Excessive Heat 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.
In some applications, other equipment inside or outside the enclosure can
produce a substantial amount of heat. In this case, place blower fans inside the
enclosure to help with air circulation and to reduce hot spots near the
controller.
Additional cooling provisions are necessary when high ambient temperatures
are encountered. Do not bring in unfiltered outside air. Place the controller in
an enclosure to help protect it from a corrosive atmosphere. Harmful
contaminants or dirt could damage components or cause improper operation.
In extreme cases, you may need air conditioning to help protect against heat
buildup within the enclosure.

12 Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 2 Installation
Notes:

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 13
Chapter 3
Power, Ground, and Wire
Wiring Requirements and
Recommendation
• 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, shrink-tubing, 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.
Wire Size and Terminal Torque
See Table 10 on page 41.
Terminal Assignment
The safety relays have eight terminal blocks: four on the top and four on the
bottom. Figure 5 on page 14 shows the front face marking of each of the relays,
including the terminal and status indicator identifications. The difference
between the two models is the standstill monitoring voltage, Vm. In
ATTENTION: Before you install and wire any device, disconnect power to the
system.
ATTENTION: 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.

14 Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 3 Power, Ground, and Wire
Figure 5, the monitoring voltage of the relay on the left is 200 mV…4V; the
relay on the right has a monitoring voltage from 20…400 mV.
Figure 5 - Relay Face and Terminal Identification
Table 3 lists the terminal functions.
Table 3 - Terminal Assignments and Functions
Connect Power Supply Power for the MSR55P 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.
Terminal Function
A1(+)-A2(-) Power supply
L1/L2/L3 Motor connections
11/12 Voltage-free redundant monitoring (non-safety) contacts (N.C.)
23/24, 33/34, 43/44 Voltage-free redundant safety contacts (N.O.)
53/54 Voltage-free monitoring (auxiliary) contact (N.O.)
X1/X2 Connection for feedback circuit
X3/X2 Reset for fault conditions.
A3(+) -A4(-) Power supply for semiconductor outputs
ON Semiconductor output indicates that safety outputs are ON.
ERR Semiconductor output indicates fault condition.
53 54 L1 L2 L3
X1 X2 X3 11 23 33 43
12 24 34 44
A3 A4 ON ERR A1 A2
OUT
ERR
PWR
53 54 L1 L2 L3
X1 X2 X3 11 23 33 43
12 24 34 44
A3 A4 ON ERR A1 A2
OUT
ERR
PWR
.2 .4
.7
MSR55P
1
1.5
23
4
.5
.3
.2 .7
ts
Vm
1
1.5
2
34
6
.5
.3
24
7
MSR55P
10
15
2030
40
5
3
.2 .7
ts
x10mVm
1
1.5
2
3
6
.5
.3
332311 43 53
342412 44 54
332311 43 53
342412 44 54
4

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 15
Power, Ground, and Wire Chapter 3
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 the Bulletin 1606 power supplies are PELV
and Class 2 compliant.
Figure 6 shows the power supply connections. Power to A1 is required to
operate the MSR55P safety relay. Power to A3 is only necessary if the solid-
state auxiliary status signals (ON and ERR) are used.
Figure 6 - Power Supply Connections
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 7 shows wiring for a single-phase, DC, and 3-phase motor.
Figure 7 - Motor Connections
24V DC
or L1 115V AC
or L1 230V AC
24V Com
or L2 (Neutral)
0 V DC
12...30V DC
A2
X1 X2
L3L2L1
X3
34 44
A1 A333
2311
2412 ON ERR A454
43 53
IMPORTANT The three connections create two safety monitoring channels. L1 is the
common to the two channels, which are L2 and L3.
L1 L2 L3
M
K1
K2
A2
X1 X2
L3L2L1
X3
34 44
A1 A3332311
2412 ON ERR A454
43 53
3-phase
L1 N
M
K1
K2
A2
X1 X2
L3L2L1
X3
34 44
A1 A3332311
2412 ON ERR A454
43 53
Single-phase and DC Motor

16 Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 3 Power, Ground, and Wire
Safety Outputs The safety outputs consist of two redundant positive-guided relays that are
connected in series. Terminals 11/12 are normally closed monitoring
(non-safety). Terminals 23/24, 33/34, and 43/44 are normally open. The
outputs can drive loads that are either AC or DC powered. Figure 8 shows
typical connections of the safety outputs to safety contactors.
Figure 8 - Safety Outputs
Derating Curve
The currents through the safety outputs are subject to derating. The derating
depends on the current through each of the outputs and the ambient
temperature. Figure 9 shows a graphical representation of the current limit over
the ambient temperature range.
Calculate the total quadratic current, which is the sum of the squares of the
currents through each of the safety outputs.
I12+ I22 + I32 = ΣI2 (A2)
Then, use the graph in Figure 9 to find the highest ambient temperature that is
allowed.
Figure 9 - Safety Output Derating Curve
Variable Description
I1, I2, I3The currents in contact paths 23/24, 33/34 and 43/44
24V DC
or L1 115V AC
or L1 230V AC
24V Com
or L2 (Neutral)
K3K2K1
A2
X1 X2
L3L2L1
X3
34 44
A1 A333
2311
2412 ON ERR A454
43 53
Total Quadratic Current Σ I2(A2)
Ambient Temperature (°C)
20
60
70
80
50
40
010 20 30 40 6050
30
10

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 17
Power, Ground, and Wire Chapter 3
• Example 1: A 5-amp load through each of the three output circuits.
52 + 52 + 52 = 75 A
From the derating curve, the maximum permitted ambient temperature
is 40 °C (104 °F).
• Example 2: A 2-amp load through each of the three output circuits.
22 + 22 + 22 = 12 A
From the derating curve, the maximum permitted ambient temperature
is 60 °C (140 °F).
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 relay contacts.
Figure 10 shows examples of output contactors with a suppression device. We
recommend that you locate the suppression device as close as possible to the
load device.
For outputs that use 24V DC, we recommend 1N4001 (50V reverse voltage)
to 1N4007 (1000V reverse voltage) diodes for surge suppression for the OSSD
safety outputs, as shown in Figure 10. 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.
Some devices, like the Bulletin 100S-CxxEJ and 100S-CxxQJ safety
contactors have built-in suppression, therefore additional suppression devices
are not needed.

18 Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 3 Power, Ground, and Wire
Figure 10 - Surge Suppression Components
Auxiliary Outputs Auxiliary contacts are intended to convey status information to the machine
control system (programmable logic controller [PLC]) or to an indicator light.
They must not be used in the safety-related circuits. Figure 11 shows an
example of the auxiliary circuits.
MSR55P safety relays have one auxiliary voltage-free contact and two
solid-state contacts.
The voltage-free contact is terminals 53/54. This contact can accommodate a
DC or AC voltage up to 230V. Terminal 53/54 closes when the safety outputs
are energized.
MSR55P safety relays have two semiconductor auxiliary outputs. The ON
output turns on when the outputs are energized. The ERR output turns on
when an error is detected by the MSR55P safety relay. The semiconductor
outputs require a separate 24V DC connection and must have a common
reference to the PLC.
Figure 11 - Example Auxiliary Circuits
K2K1
for VAC supply
V common
Metal Oxide Varistors Diodes
K2K1
for VDC supply
V common
24V DC
or L1 115V AC
or L1 230V AC
PLC
DC Input
PLC
DC or AC Input
24V Com
or L2 (Neutral) OV DC
12...30V DC
A2
X1 X2
L3L2L1
X3
34 44
A1 A333
2311
2412 ON ERR A454
43 53

Rockwell Automation Publication 440R-UM014D-EN-P - December 2019 19
Power, Ground, and Wire Chapter 3
Monitoring Input Monitoring of external devices, like safety control relays and safety contactors,
can be accomplished by adding their normally closed contacts between X1 and
X2. The safety outputs of the MSR55P safety relay are enabled only if the
feedback loop X1/X2 is closed while standstill is detected, that is the external
contactors/components are in initial state (N.C. contacts are closed).
The feedback circuit X1/X2 must be closed as long as the safety outputs are
disabled. If not, the ERR indicator shows fault code 4.
In some applications, where monitoring cannot be done, install a jumper
between X1 and X2. The jumper is shown in the No Monitoring diagram in
Figure 12.
If additional devices must be controlled, safety control relays or contactors can
be connected to the safety outputs of the MSR55P safety relay. The MSR55P
safety relay can monitor the status of these devices by connecting their voltage-
free contacts in series, as shown in the Contactor Monitoring diagram in
Figure 12.
The MSR55P safety relay is shipped from the factory with a jumper from
X1 to X2.
Figure 12 - Examples of Feedback Monitoring Circuits
ATTENTION: Terminals X1-X2-X3 have electrical connections to measuring
inputs L1-L2-L3.Voltage-free contacts that are rated for L1-L2-L3 voltage
must be used for these connections.
K3K2
K1
K2
K3
Guard Locking Device
(Power to Unlock)
Unlock Command
24V Com
A2
X1 X2
L3L2L1
X3
34 44
A1 A333
2311
2412 ON ERR A454
43 53
A2
X1 X2
L3L2L1
X3
34 44
A1 A3332311
2412 ON ERR A454
43 53
K1
24V Com
24V DC
No Monitoring Contactor Monitoring

20 Rockwell Automation Publication 440R-UM014D-EN-P - December 2019
Chapter 3 Power, Ground, and Wire
Fault Reset Input The X2/X3 connection can reset some external faults. The reset can occur
automatically or manually. The MSR55P safety relay is shipped from the
factory with a jumper from X2 and X3 for automatic reset. A voltage-free
contact can be used to reset a fault condition manually.
If control of terminal X3 must be by a push button or by a PLC via an
interposing relay, the push button or relay must have the necessary insulation
between the motor voltage and PLC potential. Figure 13 shows two typical
connections to the fault reset input.
Figure 13 - Fault Reset Circuit Examples
ATTENTION: Terminals X1-X2-X3 have electrical connections to measuring
inputs L1-L2-L3.Voltage-free contacts that are rated for L1-L2-L3 voltage
must be used for these connections.
A2
X1 X2
L3L2L1
X3
34 44
A1 A3332311
2412 ON ERR A454
43 53
Automatic Fault Reset
A2
X1 X2
L3L2L1
X3
34 44
A1 A3332311
2412 ON ERR A454
43 53
Manual Fault Reset