ABB CM-MSS.21P Thermistor motor protection relay - ATEX
Part Number: 1SVR740722R1400
Quick Summary
CM-MSS.21P thermistor motor protection relay protects motors from thermal overload in industrial drives. Engineers and maintenance teams often battle unexpected motor trips caused by temperature spikes and sensor faults, leading to costly downtime. The CM-MSS.21P carries ATEX approval and UL/CSA listings, with CE and UKCA conformity to support global compliance for motor protection relays. With a universal 24–240 V control supply and Easy Connect push-in terminals on TH35 DIN rails, it combines reliable protection with straightforward panel integration and reduced maintenance costs. This helps OEMs and service teams shorten downtime and optimize motor availability in critical automation lines across plants.
Product Information
Extended Description
1SVR740722R1400 ABB: The CM-MSS.21P belongs to the CM-MSS thermistor motor protection relay range. It operates with a rated control supply voltage of 24 - 240 V AC / DC and has a 1 n/c + 1 n/o (SPDT) output with contacts rated at 250 V / 4 A. It features one sensor circuit to monitor PTC temperature sensors and works according to the closed-circuit principle. The sensor circuit of the CM-MSS.21P is short-circuit, as well as interrupted-wire monitored and the relay will be reset automatically after the failure has been removed. This protection relay is certified according to the ATEX directive 94/9/EC. A sealable transparent cover for protection against unauthorized changes is available as accessory. The device offers maintenance free Easy Connect Technology with push-in terminals.
EAN
4013614496516
Minimum Order Quantity
1 piece
Customs Tariff Number
85364900
Data Sheet, Technical Information
Data sheet - CM-MSS.21S/P with screw or push-in terminals
Instructions and Manuals
Instruction Sheet / Manual - CM-MSS Thermistor motor protection relays | Installation instructions - CM-MSS Thermistor motor protection relays
Ex Operating Instructions
Additional information and notes on safety ATEX - CM-MSS.xx Thermistor motor protection relay
CAD Dimensional Drawing
Information - 2D and 3D files for CAD systems
Product Net Width
22.5 mm
Product Net Height
85.6 mm
Product Net Depth / Length
103.7 mm
Product Net Weight
0.118 kg
Function
1 sensor circuit | Short-circuit detection | Auto reset | ATEX approved | Dynamic interrupted wire detection | Non-volatile fault storage
Rated Control Supply Voltage (Us)
24 ... 240 V AC/DC
Rated Operational Voltage
Auxiliary Circuit 250 V AC
Rated Frequency (f)
Supply Circuit 15 ... 400 Hz
Output
1 n/o + 1 n/c contact
Terminal Type
Screwless Terminals
Rated Operational Current AC-12 (Ie)
(230 V) 4 A
Rated Operational Current AC-15 (Ie)
(230 V) 3 A
Rated Operational Current DC-12 (Ie)
(24 V) 4 A
Rated Operational Current DC-13 (Ie)
(24 V) 2 A
Minimum Switching Capacity
24 V | 10 mA
Rated Impulse Withstand Voltage (Uimp)
Output Circuit 1 / Output Circuit 2 4 kV | Output Circuit 4 kV
Rated Insulation Voltage (Ui)
Measuring Circuit / Output Circuit 300 V | Output Circuit 1 / Output Circuit 2 300 V | Supply Circuit / Measuring Circuit 300 V | Supply Circuit / Output Circuit 300 V
Degree of Protection
Housing IP50 | Terminals IP20
Overvoltage Category
III
Pollution Degree
3
Short-Circuit Protective Devices
Output Circuit NC - F Type Fuses 10 A | Output Circuit NO - F Type Fuses 10 A
Electrical Durability
AC-12 100000 cycle
Mechanical Durability
Nr. Operations 30000000 cycle
Connecting Capacity
Flexible 2x 0.5 ... 1.5 mm² | Rigid 2x 0.5 ... 1.5 mm²
Wire Stripping Length
8 mm
Mounting Position
1 ... 6
Mounting on DIN Rail
TH35-7.5 (35 x 7.5 mm Mounting Rail) acc. to IEC 60715 | TH35-15 (35 x 15 mm Mounting Rail) acc. to IEC 60715
Standards
CAN/CSA C22.2 No.14 | EN 50495 | IEC/EN 63000 | IEC/EN 60079-7 | IEC/EN 60947-5-1 | IEC/EN 60947-8 | UL 508
Maximum Operating Voltage UL/CSA
Output Circuit 300 V AC
Contact Rating UL/CSA
B300
Connecting Capacity UL/CSA
Flexible 2x 18-16 AWG | Rigid 2x 20-16 AWG
Pilot Duty UL/CSA
B300
Flammability According to UL94
V-0
Ambient Air Temperature
Operation -25 ... +60 °C | Storage -40 ... +85 °C
Maximum Operating Altitude Permissible
Without Derating 2000 m
Conflict Minerals Reporting Template (CMRT)
CMRT - Conflict Minerals Reporting Template
REACH Declaration
REACh Info for Electronic Relays and Controls
RoHS Information
RoHS Declaration of conformity for Electronic Relays and Controls
RoHS Status
Following EU Directive 2011/65/EU and Amendment 2015/863 July 22, 2019
Toxic Substances Control Act - TSCA
Toxic Substances Control Act (TSCA) declaration for Electronic Relays and Controls
ATEX Certificate
EU Type Examination Certificate_TPS_18_ATEX_044254_0018_X
CB Certificate
CB_DK-40837-UL
CCC Certificate
CCC Certificate - Measuring and Monitoring Relays CM-PFS.x, CM-MSS.xxx, CM-MSS, CM-ENS, CM-ENS up/down
CQC Certificate
CQC Certificate, Measuring and Monitoring Relays, CM-PFS.x, CM-PFS, CM-MSS.xyz, CM-ENS, CM-ENS up/down, Made in Germany
cULus Certificate
cULus508_20140912-E140448
Declaration of Conformity - CCC
CCC Declaration of Conformity, Measuring and Monitoring Relays, CM-PFS.x, CM-PFS, CM-MSS.xyz, CM-ENS, CM-ENS up/down, Made in Germany
Declaration of Conformity - CE
EU Declaration of Conformity - CM-MSS.xxx thermistor motor protection relay with ATEX
Declaration of Conformity - UKCA
1SVD981007-10
DNV GL Certificate
DNV GL Certificate Thermistor motor protection relays
Package Level 1 Units
box 1 piece
Package Level 1 Width
97 mm
Package Level 1 Depth / Length
30 mm
Package Level 1 Height
109 mm
Package Level 1 Gross Weight
0.145 kg
Package Level 1 EAN
4013614496516
Object Classification Code
B
ETIM 7
EC002568 - Relay for thermistor protection (PTC)
ETIM 8
EC002568 - Relay for thermistor protection (PTC)
ETIM 9
EC002568 - Relay for thermistor protection (PTC)
eClass
V11.0 : 27371503
UNSPSC
39122331
E-Number (Finland)
2712398
E-Number (Norway)
4188185
E-Number (Sweden)
3860721
Feature: Versatile control supply 24–240 V AC/DC. Business impact: Reduces spare parts and simplifies panel design. Application: Ideal for motor protection in mixed-voltage drives across pumps, fans, and conveyors. Feature: 1 n/o + 1 n/c contact rated up to 4 A at 230 V. Business impact: Enables direct switching of auxiliary circuits and interlocks with safe, dependable operation. Application: Used for motor starters, interlocks, and control circuits in packaging lines and material handling. Feature: Single PTC sensor circuit with short-circuit, interrupted-wire detection and auto reset. Business impact: Lowers nuisance trips and enables automatic fault recovery, improving line uptime. Application: Critical for motors in environments with wiring vulnerability or fluctuating temperatures. Feature: ATEX certification and UL/CSA/CE/UKCA compatibility. Business impact: Supports compliant installations in hazardous zones and global markets, reducing risk and certification time. Application: Suitable for food processing, chemical, and mineral handling plants with strict safety requirements. Feature: Easy Connect technology with screwless terminals and 24–240 V DIN rail mounting. Business impact: Fast installation, fewer wiring errors, and easier field maintenance. Application: Ideal for new builds and retrofits in control panels using TH35 DIN rails (TH35-7.5 or TH35-15). Feature: Built for durability: IP50 housing, AC-12 durability up to 100000 cycles, and mechanical durability of 30,000,000 operations. Business impact: Long service life reduces maintenance cycles and total cost of ownership. Application: Reliable protection in continuous operation environments like conveyors and blowers. Paragraphs continue with additional context: The device also supports 230 V AC and 24 V DC operation with appropriate current ratings (AC-12 4 A, AC-15 3 A; DC-12 4 A, DC-13 2 A), ensuring compatibility with common motor control schemes. Its compact footprint (22.5 mm width, 85.6 mm height, 103.7 mm depth) and 0.118 kg weight make it a practical drop-in for crowded control panels and compact motor starters. All of these features collectively enable safer, more reliable motor protection with predictable maintenance planning.
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FAQs
Yes. The CM-MSS.21P is designed for mounting on standard TH35 DIN rails (TH35-7.5 and TH35-15). It also features Easy Connect push-in terminals, which speeds wiring and reduces field installation errors when integrating into motor control panels.
The relay provides 1 normally open and 1 normally closed contact (1 n/o + 1 n/c) with a rated operational current of up to 4 A at 230 V for AC-12 and 3 A for AC-15, plus 4 A for DC-12 and 2 A for DC-13. It accepts a control supply of 24–240 V AC/DC and offers reliable switching for auxiliary circuits.
Best suited for motor protection in pumps, fans, conveyors, and general machinery where thermal overload protection is critical. Its PTC sensor circuit, auto reset, and ATEX certification make it ideal for both standard industrial environments and hazardous zones requiring stringent safety compliance.
It carries ATEX certification for explosive atmospheres, CE marking for European conformity, UKCA for the UK, and UL/CSA listings for North American compliance. These certifications reduce validation time, enable cross-border deployments, and help ensure safe operation under local regulatory requirements.
The device offers maintenance-free Easy Connect technology, auto fault reset, and non-volatile fault storage, reducing downtime and service interventions. Its durable design and long electrical/mechanical lifetimes translate to lower replacement costs and improved motor availability across production lines.