ECE5320 Mechatronics Assignment#01: Literature Survey on Actuators Solid State Relay

1. ECE5320 MechatronicsAssignment#01: Literature Survey on ActuatorsSolid State Relay Prepared by: Tyler Whipple Dept. of Electrical and Computer Engineering Utah State University (435)797-3054 (ECE Dept.) 3/20/2012

2. Outline • Reference list • To further explore • Major applications • Basic working principle illustrated • A typical sample configuration in application (application notes) • Major specifications • Limitations • And many more relevant issues in applications (such as, how to choose, cost information, where to buy etc.) ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

3. Reference List • Why use solid state relays http://www.crydom.com/en/Tech/Tips/why%20use%20a%20solid%20stat%20relay.pdf • General information on solid state relays http://en.wikipedia.org/wiki/Solid-state_relay • Major Specifications http://www.globalspec.com/SpecSearch/SearchForm/ electromechanical_components/relays_timers/solid_state_relays • How to select SSR http://www.automation.siemens.com/mcms/industrial-controls/en/controls/solid-state- switching-devices/resistive-inductive-loads/solid-state-relays/select/Pages/default.aspx ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

4. To Further Explore • Overview of solid state relay http://www.omega.com/temperature/z/pdf/z124-127.pdf ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

5. Major Applications • Used as an electric on-off control device that uses a low energy activation signal to complete the circuit with a higher load • Used in heating systems in conjunction with a controller • Used in explosive environments due to the inability to spark on switching • Used to eliminate mechanical vibrations from switching ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

6. Basic Working Principal • Electronic switching device that uses a low power input signal to control a higher energy load • Control loop and load loop separated but coupled together in different ways, one being optical coupling to switch the load ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

7. Optically Coupled Solid State Relay The schematic shows a solid state relay that uses the control voltage to power an LED that switches a photo voltaic diode Figure from: http://en.wikipedia.org/wiki/File:SolidStateRelay-Diagram.svg ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

8. Typical Solid State Relay http://www.futurlec.com/Pictures/Solid_State_Relay_300.jpg ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

9. Advantages to SSRs • Long service length • No moving parts to wear • No arcing contact surfaces to diminish conduction • 50 times longer than electromechanical relay • No audible operational noise • Require less power than Electromechanical relays • High Compatibility with Control Systems • A/C and D/C operation allows for control by PLCs or limit switches and thermal switch ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

10. Advantages to SSRs • Quick response time <100 μs • Precise control of power to load • No contact bounce • Low Power Consumption • Ideal for harsh Environments • No electrical arcing • Not susceptible to vibration and magnetic fields ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

11. Limitations • Electrical similarities of a semiconductor instead of mechanical contact • When closed, both increased resistance and electrical noise • Generates Heat • In open state, SSR has lower resistance and very small reverse leakage current • Likely to fail in closed instead of open state, unlike electromechanical relays ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

12. Sample Configuration Diagram showing the use of a SSR to heat a vacuum chamber using a resistive heater ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

13. Major Specifications • Maximum Current • Input/Output Voltage Type (A/C or D/C) • Load Voltage • Input Voltage/Current Range • Isolation Type (Optically, Transformer, None) • Operating Temperature ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

14. Mounting • Solid state relay can be mounted in any orientation (vertical, upside down, etc.) and preform optimally • Because of solid state relays switching method, they are always partially “on” but with higher resistance. This means the SSR is generating heat at all times • Due to the generated heat, it is necessary to mount the solid state relay to a heat sink with appropriate thermal properties for the application ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

15. Size • Due to the nature of how solid state relays operate, they are generally smaller than other relays • This is due to the utilization of semiconductors instead of mechanical means of switching ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

16. Heat Sink • Since solid state relays generate heat in operation, a heat sink is usually required to help dissipate excess heat to maintain optimum operating temperature http://parts.digikey.com/1/parts/1715701-relay-ssr-spst-65a-w-heatsink-zc-hs072-d2490.html ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

17. Selection Process for SSR’s • Determine the systems current, voltage and load • Select a solid state relay rated higher than the system’s current for the configured load • Find heat sink with necessary thermal properties • Check diagrams to determine proper relay sizing ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

18. Cost Information • Solid State Relays • Generally about $20 for 10 A and $100 for 100 A • Prices vary with required amperage as well as application requirements, e. g. optical isolation • Heat Sink • $19-$30 depending on heat dissipation required ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

19. Where to Buy • Omega • Selection of many types of solid state relays of varying amperage ratings and application • Has heat sinks as well as any other desired accessories • Suggests controllers for selected SSRs and applications • Newark • Discount on bulk purchases ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators

20. Alternative: Electromechanical Relay Comparing SSR to EMR Solid State Relay Electromechanical Relay Much lower On resistance Less signal attenuation Greater load current capability Lower output capacitance Better for high frequency applications Lower price • Longer service life • Higher voltage isolation • Smaller Dimensions • Lower required input signal ECE5320 Mechatronics. Assignment#1 Survey on sensors and actuators