Eurotherm Harmony Solid State Relays

Eurotherm Solid State Relays (SSR)

Harmony includes intelligent connected products and edge terminals that visualize, gather and process data, enabling informed operator decisions
Applications: Packaging, plastic molding, injection molding, HVAC, medical equipment, textile, heating furnaces, and more!
Highlights: wide range of options from DIN rail to panel mount, single-phase and three-phase options, current ratings from 0.1A to 125A, simplified installation and mounting, flexible and robust wiring, easy debugging and commissioning, and a wide range of standards and certifications

Eurotherm Harmony Solid State Relays

The Harmony Solid State Relays series offers slim interface (SSL), modular DIN rail (SSD, SSM) and panel mount (SSP) SSRs that provide complete, compact, and innovative solutions for a wide variety of applications with interfacing control and load switching.


  •  Conforms to a wide range of internationally recognized standards and certification
  • Complies with IEC 61373 for railway and rolling stock application (SSD range only)
  • Electromagnetic compatibility complying with IEC 60947-4-3 standard (SSD range only)
  •  Compact solution with 6 mm width for SSL range reduces space and allows easy mounting on the socket
  • Pre-mounted version (relay mounted on socket) available in SSL range to ease selection and save installation time
  • Integrated heatsink in SSM and SSD ranges eliminate the need for complex thermal calculation, hence could be directly plugged into control panels for use
  • Complete solution – 1 and 3-Phase, slim, modular DIN rail and panel mount offer
  • Besides standard screw, spring terminals are available in SSL and SSD ranges to save wiring time
  • Telescopic screws in SSP and SSD ranges to prevent screw jams and facilitate the use of lug terminals (cable ends, fork lug, ring lug)
  • Relay and Contactor configuration in SSD range to meet different wiring preferences and save time
  • Smart diagnostic feature in SSP1.S range with embedded visual indication and test button for easy commissioning and immediate response to abnormalities.

Benefits of Harmony SSRs vs Electromechanical Relays (EMRs)

  • Long lifetime: Since there are no moving parts inside solid state relays, they are not subject to any contact failure, mechanical strain or corrosion. Solid state relays can operate for millions of cycles with no deterioration in performance and the lifetime is said to be 50-100 times that of electromechanical relay. Hence solid state relays are ideal for repetitive applications and when low maintenance is preferred.
  • Fast switching: Due to the absence of movable parts, solid state relays have a very fast response time. This means power to a load can be applied and removed very quickly and precisely, which is especially important for applications that requires quick on-off switching.
  • Shock and Vibration resistant: Without movable parts, solid state relays will not bounce electrically or mechanically. This makes them highly susceptible to erratic conditions in demanding and high vibration environments. For instance, Schneider Electric’s SSD solid state relays complies with IEC 61373 for railway & rolling stock application.

Harmony Solid State Relays we recommend!


Harmony, Solid state relay, 20 A, DIN rail mount, zero voltage switching, input 4…32 V DC, output 48…600 V AC.

Replaces the Zelio SSM1A120BD


Harmony, Solid state relay, 35 A, DIN rail mount, zero voltage switching, input 4…32 V DC, output 48…600 V AC

Replaces the Zelio SSM1A430BD


Harmony, Solid state relay, 45 A, DIN rail mount, zero voltage switching, input 4…32 V DC, output 48…600 V AC

Replaces the Zelio SSM1A445BD


Harmony, Solid state relay, 60 A, DIN rail mount, zero voltage switching, input 4…32 V DC, output 48…600 V AC

Replaces the Zelio SSM1A455BD

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