There are many applications and circumstances where switching devices are required for proper operation, controlling and isolating the high power and low power systems. The most widely used switching devices are electromechanical relays and solid state relays. In this work, analysis and implementation of solid state relays over electromechanical relays with respect to instantaneous current supply inindustrial application is conducted and compared. For this purpose, an experimental setup is arranged for switching operation of electromechanical relays and solid-state relays.The results of voltage and the current transients are analyzed and compared. It was observed that there are no transients occurred during switching of solid state relays where as during switching of electromechanical relay transients observed in volatge and current waveforms. So, it is advisable to use the solid state relays over electromagnetic relay for safe and smooth operation of the system.

1. International Journal of Modern Research in Engineering & Management (IJMREM)
||Volume|| 2||Issue|| 2 ||Pages|| 6-11 || February 2019 || ISSN: 2581-4540
www.ijmrem.com IJMREM Page 6
Analysis and Implementation of Solid-State Relays in Industrial
application For Instantaneous Current Supply
1,
Fawad M.Memon 2,
Engr.Noor Nabi Shaikh, 3,
Engr. Nizamuddin Channa 4,
Engr. Shafqat Hussain Memon
1,
Student ME (Electrical Power) IICT, Mehran UET Jamshoro;
2,
Assistant Prof. Electrical Engg. Department Mehran UET Jamshoro;
3,
Technologist Electrical Engg. Department Mehran UET Jamshoro;
4,
Lab Engr. Electrical Engg. Department Mehran SZAB Campus Khairpur
--------------------------------------------------ABSTRACT--------------------------------------------------------
There are many applications and circumstances where switching devices are required for proper operation,
controlling and isolating the high power and low power systems. The most widely used switching devices are
electromechanical relays and solid state relays. In this work, analysis and implementation of solid state relays over
electromechanical relays with respect to instantaneous current supply inindustrial application is conducted and
compared. For this purpose, an experimental setup is arranged for switching operation of electromechanical relays
and solid-state relays.The results of voltage and the current transients are analyzed and compared. It was observed
that there are no transients occurred during switching of solid state relays where as during switching of
electromechanical relay transients observed in volatge and current waveforms. So, it is advisable to use the solid
state relays over electromagnetic relay for safe and smooth operation of the system.
KEY WORDS: Electromagnetic relay , solid state relay, instantaneous current, transients.
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Date of Submission: Date, 30 January 2019 Date of Accepted: 03. February 2019
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1. INTRODUCTION
In the context of switching small power circuits, different components exist such as solid state and electro-
mechanical switches [1]. The electromechanical relays or contactors are widely utilized in different applications
in industrial, commercial and residential level. Even the concept of electromechanical is not new one it is from
nineteenth century, despite this it still provides many advantages over semiconductors-based switching devices
such as: Less energy losses, ability to block current, to withstand voltage stresses in both directions, less costly
and absence of drivers to be activated. Due to these characteristics these are mostly utilized in products involving
electric and electronic regulation.
In spite of all above features, electromechanical devices offer some drawbacks due to their mode of operation
comparative to solid-state switches such as these have slower response, presence of moving parts, mechanical
failure, more chances of wear and tear and less life [2]. Besides this, when the movable parts strikes the fixed part
strong bounces are produced in each switching hence that results in production of additional wearing and a noise
which causes problems in many applications. As a result, solid-state switches are preferred than the
electromechanical devices. [3]
Protective Relay: It is known that Relay is one of the best protective devices and it is used for detection purpose
whenever the circuit breaker is used for interruption purpose. A relay is basically act as a switch and based on the
principle of electromagnetic induction. The switching between 0 and 1 is basically done with the help of
electromagnetic induction; hence it shows an automatic system. The basic fundamental requirements of relay are
selectivity, sensitivity, speed, reliability, simplicity & economy. The selectivity is basically used to select the
zones of protection. The relay requirements play an important role when there is the requirement to control large
amount of current, voltage & speed. The relays are also used for controlling and regulating power distribution &
generation. [4]
Types of Relays: Basically, there are two basic categories of relay which are based on its construction named as;
electromechanical andstatic relays;
Electromagnetic relays: When the electromagnetic gets energized the current is flowing and hence the two
contacts are being twisted together. The integration between the controlling circuits and power circuits can be
done easily by using electromechanical relays.

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The superior merits of electromechanical relays are that there is no need of heat sink, there is low cost, there is
availability of many poles and there is easy on and off control either in AC or DC [6].
Solid state relays: In solid state relays, the measurement of electrical quantities is done by static circuit which
gives output signal for the circuit breaker tripping is known as static as there is no moving part in solid state relay.
In solid state relay, there is use of an analog electronic device instead of using magnetic coil in order to create the
characteristics of relay and the voltage and current waveforms are being monitored by using analog circuits. In
these relays, there is no any effect of jerk or gravity. Solid state relays are also used in order to control the electrical
noises and hence it has high reliability and longer life. It has fast response as compare to other relays [6].
II. EXPERIMENTAL DETAILS
The hardware prototype model is developed for comparative analysis of electromechanical and solid-state relays
with respect voltage and current transients for the industrial applications. The following are the block diagrams to
represent the prototype models developed for electromagnetic and solid state relays are shown in figures 1 and 2
respectively.
Fig. 1 Block diagram representation for switching of electromagnetic relay
Fig. 2 Block diagram representation for switching of solid state relay
Experimentalsetup with electromagnetic relay : The experimental setup developed for electromagnetic relays
is shown in following figure 3. It consists of following hardware components as briefly described below.

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Fig.3Experimental setup due to switching of electromagnetic relay
System Description :System developed for testing of solid state and electromagnetic relays in this research work
comprises of main components described below.
• Power Supply : In this circuit power supply works as an electric power converter. It receives Ac power
from Source than convert it into dc.
• Voltage divider circuit : This simple circuitryis used in this prototype model to turn large voltage into
smaller one.
• Digital Timer Module : It switches the relay with different time interval of time. It is a LED display
module through the time is adjusted at different intervals.
• Oscilloscope : It used to display and analyze the waveforms of voltage and currents transients.
• Ammeter: It is a measuring instrument which is used to measure current in the circuit.
• Inductive Load :It is used for testing of the both relays at different instants.
Electromagnetic Relay LS18A (MC-18b) : The electromagnetic relay (i.e. LS18A (MC-18b) is prefered to use
in this work because of its various features such as compact size, simplicity, high efficiency and reliability.
Follwings table represents the specifications and ratings of electromagnetic relay (i.e. LS18A (MC-18b) used in
this work.
Table. No. 1 Specifications and Ratings of Electromagnetic Relay (LS18A (MC-18b)
Model # MC-18b-AC
Coil Voltage 120VAC
Amp Rating 18A
Frame Size 22AF
Auxilary Contacts 1NO 1NC
Terminal Type Screw type terminal
Weight (lbs.) 2
Prototype setup with solid state relay : The experimental setup developed for electromagnetic relays is shown
in following figure 4.
Fig.4 Experimental setup due to switching of solid state relay

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3.2.1Solid State Relay FOTEK (SSR-40DA): The single phase arduino based driven solid-state relay (i.e.
LS18A (MC-18b) is preffered to use in this prototype model because of its various features such as high ultra
insulation resistance (50MΩ/500V) , high dielectric (2.5kV), high suge current and surge volatge duration by
snubber circuit.
Table. No. 2 Specifications and Ratings ofSolid State Relay FOTEK (SSR-40DA)
Model # SSR-40 DA
Control Mode DC-AC
Load Voltage 24-380VAC
Load Current 40A
Control Voltage 3-32VDC
Control Current DC3-25mA
Working voltage On voltage
On voltage ≤1V
One-off Time ≤10ms
Off leakage Current ≤2mA
Installation Method Bolt Fixed
Working Indication LED
III. RESULTS &DISCUSSIONS
Switching with Electromagnetic Relays: The electromagnetic relay is switched at different instants to analyse
the transient behaviour. After switching of electromagnetic relay the voltage trasient and current transient are
observed.
Voltage trasients due to the electromechanical relays :These are the results of the voltage transients due to
switching of electromagnetic relay as shwon in figure 5.It is clearly seen that the trasient voltages are more than
the peak voltages.The value of peak votages in these pictures are 200v and transient voltages are more than the
400 v. i.e almost double than the paek voltages.In our industries when trasients occurred the motor runs at high
temprature.due to these transients the normal timing of motor intrupted
(a) (b)
Fig.5 Voltage trasients due to the switiching of electromechanical relay

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Current trasients due to the switiching electromechanical relays : It is clearly observed from follwing results
(a and b ) shown in the figure 6 that there are current trasients due to the switichingelectromechanical relays.
(a) (b)
Fig.6 Current trasients due to the switiching of electromechanical relay
Switching of Solid State Relay : The solid state relay is switched at different instants to analyse the transient
behaviour. It is clearly seen from followong results (a and b) shown in figure 7 that due to the switching of solid
state relay there is no transient in volatge and currents waveforms.
(a) (b)
Fig.7 No trasients due to the switiching of solid state relay
IV. CONCLUSION
Solid state and electromagnetic relays are widely used for power system protection. Operation of these relays are
associated to abnormal conditions. In this work, hardware prototype setup is developed for testing both types of
relays to analyse transient response. After switching of electromagnetic relays at different instants it was observed
that the transients were generated in the electromagnetic relays. These transients were many times than the peak
voltage which cause the damage of electronic devices and control equipment whereas it was observed from the
result of switching of solid state relays that there are no transients occurred. So, it is advisable to use the solid
state relays over electromagnetic relay for safe and smooth operation of the system.
REFERENCES
[1] Copt, Florian, Christian Koechli, and Yves Perriard. "Electrostatically actuated MEMs relay for high
power applications." Electrical Machines and Systems (ICEMS), 2016 19th International Conference on.
IEEE, 2016.
[2] Fernández, M., Perpiñá, X., Vellvehi, M., Jordà, X., Cabeza, T. and Llorente, S., 2017, September.
Analysis of solid state relay solutions based on different semiconductor technologies. In Power
Electronics and Applications (EPE'17 ECCE Europe), 2017 19th European Conference on (pp. P-1).
IEEE.

6. Analysis and Implementation of Solid-State Relays…
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[3] Edgar Ramirez-Laboreo, Carlos Sagues, Sergio Llorente ‘’A new model of electromechanical relays for
predicting the motion and electromagnetic dynamics’’2015-IEEE Journal -0397.
[4] Verma, N., Gupta, K. and Mahapatra, S., 2015. Implementation of Solid-State Relays for Power System
Protection. International Journal of Scientific & Technology Research, 4(6), pp.65-70.
[5] Blackburn, J.L. and Domin, T.J., 2006. Protective relaying: principles and applications. CRC press.
[6] Kadah, A.S., Kadah and Andrew S., 1997. Solid state/electromechanical hybrid relay. U.S. Patent
5,699,218.