Design of Programmable Inductive Voltage Divider Using Minimum Inductive Elements

International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2277-3878, Volume-9 Issue-2, July 2020

Design of Programmable Inductive Voltage Divider using Minimum Inductive Elements

A. Eliwa Gad, M. Helmy A. Raouf, A. A. Ammar

1Abstract: In this paper, a proposed inductive voltage divider is switches as shown in Fig.1, therefore variable contact described to be operated manually and automatically, which is resistance in such switches often greatly affects the stability not provided by the ordinary decade inductive voltage dividers. of the voltage ratio measurements. Also, the conventional Design of that programmable inductive voltage divider (PIVD) is investigated and presented in detail. The introduced PIVD mainly DIVD cannot be used in automated measurement systems or consists of inductive elements, relays, microcontroller to get the checking the linearity of their devices [11]. required output voltage ratios through its three stages. This PIVD is designed to produce 999 steps in the range from 1×10-3 to 999×10-3 output ratios using minimum inductive elements and reed relays. Simulation of this PIVD has been performed and illustrated as well as practical design components are discussed in detail. Keywords: Programmable inductive voltage divider; Reed relays; simulation; Microcontroller; voltage ratio

I. INTRODUCTION AC voltage ratios can be obtained using different techniques such as resistive, capacitive and inductive voltage dividers

(IVDs). Ideally inductive and capacitive dividers do not dissipate any power, but practically they dissipate some Fig.1: Conventional manual inductive voltage divider power because they have some internal parasitic resistance. with 0.582 selected ratio. On the other hand, resistive voltage dividers consume the energy in terms of heat. These dividers are not suitable to To solve the problems of the traditional DIVD, a operate at high frequencies because the parasitic elements programmable inductive voltage divider has been introduced are significant so the voltage division may be vastly in this paper. The demonstrated PIVD has three stages and different[1]. Particularly for accurate electro-magnetic each produces 10 different ratios. First and second stages have the same design and each has six inductive elements, measurements, IVDs are recommended due their high input impedance, low output impedance, high accuracy and better whereas the last stage has only five inductive elements. Main idea of the proposed PIVD design is using minimum stability[2]. Generally, IVDs are widely known as the precise ratio reference with better stability and used to inductive elements to obtain the required output voltage provide ac voltage and power standards[3]. One of the IVD ratios with different control methods, which is innovative applications is the evaluation of a transformer ratio of a work. The PIVD can be controlled manually or bridge used for accurate impedance measurement[4], [5]. In automatically to be used in different automation addition, a precise IVD is an important component of applications. This PIVD is controlled by using a group of sinusoidal and non-sinusoidal power measurement reed relays through a microcontroller to produce 999 output systems[6]. Configuration of a conventional decade ratios. The microcontroller drives the reed relays through a inductive voltage divider (DIVD) is shown in Fig. 1. specially prepared C-program. The PIVD design has been Generally, each stage of such inductive voltage divider simulated and validated by using Proteus program as generates 10 voltage ratios using 11 inductive elements [7]. explained and presented in detail. There is a mutual inductance between coils of these inductive elements so, it is not ideal inductive divider [8]. II. DESIGN AND STRUCTURE OF THE PROPOSED This leads to increase electromagnetic interference, residual PIVD capacitive and resistive values between its inductive Design of the PIVD is mainly based on four parts; inductive elements[9]. In addition, effect of the accumulation error elements, reed relays, microcontroller and output ratios. reduces the accuracy of output voltage[10]. In such old Firstly, the idea of reducing the number of inductive dividers, each stage is controlled manually using a dial elements is important to improve the performance of this PIVD as will be clearly explained during the last section of Revised Manuscript Received on June 22, 2020. this paper. As demonstrated in Fig. 2, the PIVD has been 1A. Eliwa Gad, Department of Electrical Quantities Metrology, National Institute of Standards (NIS), Giza, Egypt. Email: designed by three stages. [email protected] M. Helmy A. Raouf, Department of Electrical Quantities Metrology, National Institute of Standards (NIS), Giza, Egypt. Email: [email protected] A. A. Ammar, Department of Electrical Engineering, Al-Azhar University, Cairo, Egypt. Email: [email protected]

Published By: Retrieval Number: B3930079220/2020©BEIESP Blue Eyes Intelligence Engineering DOI:10.35940/ijrte.B3930.079220 897 and Sciences Publication

Design of Programmable Inductive Voltage Divider using Minimum Inductive Elements

First and second stages have six inductive elements for each, III. SETTING OF THE PIVD RELAYS while the last stage has only five inductive elements. This The inductive elements are connected in series through divider is designed to achieve high input impedance and low different groups of reed relays. The first stage has the same output impedance due to its special design. So, the inductive number of relays as the second stage, whereas the third stage elements values of the proceeding stage depend on the has a relatively smaller number of relays. This last stage is values of inductive elements of the preceding stage by designed to produce the final output of the required divided dividing its values by 5. For example, the first stage has voltage. Figure 3 shows relays states of the first stage which nominal inductive values of L =L =L = L, L =L = 2L and 1 2 3 4 5 are selected to produce the nominal ratios from 1×10-1 to L = 4L, also the nominal inductive values of the second 6 9×10-1 in addition to the ratio of one where the whole input stage are L =L =L = L/5, L =L = 2L/5 and L = 4L/5, but 7 8 9 10 11 12 voltage, of a voltage source, is transferred to the divider the nominal inductive values of the last stage are L =L = 13 14 output terminals. L/25, L15=L16= 2L/25 and L17= 4L/25 .

Fig. 3: Relays states of the first stage. Fig.2: Schematic diagram of the PIVD. The first stage is connected to the second stage through two The number of the PIVD output ratios depend on the relays, Re15 and Re16, as shown in Fig.2. The nominal ratios S number of stages which produce 10 output voltage ratios, from 1×10-2 to 9×10-2 are obtained by setting the relays of where S is the number of stages. The input voltage of the second stage as depicted in Fig.4. In these two stages, proceeding stage depends on voltage across only one the steps values of 4,6,7 and 8 are obtained by using six inductive element. For example, input voltage of the second relays for each step, but only two relays are used to produce stage equal to the voltage across L5 as demonstrated in Fig.2, each value of the remaining steps as demonstrated in Figs. 3 where VL5 is equal to 0.1Vin. This voltage can be and 4. represented by the following equation:

푉퐿5 = 푉퐿7 + 푉퐿8 + 푉퐿9 + 푉퐿10 + 푉퐿11 + 푉퐿12 (1)

A group of reed relays produce output ratios through a microcontroller that has been programmed by a special C- program. Each output ratio depends on voltage across one or more inductive elements. The first stage output ratios can be determined using the following equations: 푉 푅푎푡푖표 0.1 = 퐿1 (2) 푉푖푛 푉 +푉 푅푎푡푖표 0.2 = 퐿1 퐿2 (3) 푉푖푛 푉 +푉 +푉 푅푎푡푖표 0.3 = 퐿1 퐿2 퐿3 (4) 푉푖푛 푉 푅푎푡푖표 0.4 = 퐿6 (5) 푉푖푛 Fig. 4: Relays states of the second stage. 푉 +푉 +푉 +푉 푅푎푡푖표 0.5 = 퐿1 퐿2 퐿3 퐿4 (6) 푉푖푛 The third stage has a relatively smaller number of relays 푉퐿4+푉퐿6 푅푎푡푖표 0.6 = (7) with respect to the other stages. This stage is designed with 푉푖푛 푉 +푉 +푉 푅푎푡푖표 0.7 = 퐿3 퐿4 퐿6 (8) different construction where the final divided voltage is 푉푖푛 obtained at the divider output terminals. Furthermore, it has 푉 +푉 +푉 +푉 푅푎푡푖표 0.8 = 퐿2 퐿3 퐿4 퐿6 (9) different settings of relays to obtain the output ratios from 푉푖푛 -3 -3 푉 +푉 +푉 +푉 +푉 1×10 to 9×10 as illustrated in Fig.5. 푅푎푡푖표 0.9 = 퐿1 퐿2 퐿3 퐿4 퐿6 (10) 푉푖푛 Similarly, for other stages; their output ratios can be obtained by the same equations using the schematic diagram illustrated in Fig.2.

Published By: Retrieval Number: B3930079220/2020©BEIESP Blue Eyes Intelligence Engineering DOI:10.35940/ijrte.B3930.079220 898 and Sciences Publication International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2277-3878, Volume-9 Issue-2, July 2020

Fig. 5: Relays states of the third stage. Fig.6: Block diagram of the PIVD and related devices. In this stage the 0, 0.001, 0.003, 0.004, 0.008 ratios values are obtained by using only one relay for each step, but the The three stages that have 17 inductive elements are used to other ratios values are produced by using three relays for design the PIVD. For the first stage; the inductive elements each step. Accordingly, each stage produces nine output are three 100 mH, two 200 mH and only one 400 mH. As ratios, but totally 999 output ratios could be obtained by well as, the second stage has inductive elements values using all possible combinations of the three stages. which are three 20 mH, two 40 mH and only one 80 mH. But inductive elements values of the output stage are two 4 IV. SIMULATION OF THE PIVD WITH ITS mH, two 8 mH and only one 16 mH. The inductive elements MEASUREMENT SYSTEM of each stage are connected in series by using the reed relays. While the input of each stage is connected in parallel The new design of the PIVD is fully simulated using the to one of the inductive elements of the previous stage as Proetus program. This simulation is mainly based on some shown in Figs. 2 and 7. The microcontroller, modules; voltage source, inductive elements, reed relays, ATMEGA8515, could be programmed through a prepared C microcontroller, keypad, LCD and measuring device as language program which has been used to control the reed clearly defined through the block diagram demonstrated in relays to generate the required voltage ratios manually or Fig. 6. For automatic control; a computer is connected to the automatically. Manual control could be obtained using the PIVD. Fig. 7 shows user interface of the PIVD simulation PIVD keypad. Automatic control will be obtained using a which is designed with 37 relays to control the three stages special computer program via Serial-USB cable to derive to obtain zero ratio in addition to nine voltage ratios from the microcontroller and generate the output ratios each stage. They have four contact forms, SPST, SPDT, automatically. Then a voltmeter will be connected to the DPDT, DPST, that are controlled by using one PIVD output terminals to measure the divided voltage as microcontroller. All of the 999 ratios are produced by the depicted in Fig.6. Therefore, this PIVD has more facilities to maximum different combinations of the three PIVD stages. be used in automated measurement systems and other useful applications.

Re29 Re1 Re14 Re15 L6 Re28 400m Re13 L12 80m Re27 L16 8m

Re35 L4 Re12 200m Re11 L7 Re26 40m Re25 L5

L11 L17 7

200m 3 16m 40m e R Re34 L3 100m L8 Re9 Re10 20m

+ Re23 Re24 i V2 L14 +500

AC Volts VSINE 4m Re33

- i L2 100m Re7 L9 Re8 20m Re21 Re22 L15

8m Re32

e R

L1 100m L10 Re5 L13 Re6 20m Re31 Re19 4m Re20 o+

+347 AC Volts

Re2 Re16 Re3 Re4

Re17 Re18 - Re30 o

RL2(C1)

0 8 7 6 5 4 3 2 1 0 8 7 6 5 4 3 2 1

1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0 7 6 5 4 3 2 1

U1 8

1 1 1 1 1 1 1 1 1

0 8 7 6 5 4 3 2 1

1 1 1 1 1 1 1 1

10 1

C C C C C C C C C C C C C C C C M

COM M

2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

1 U3 U5 O

RL1 1 18 O

C C C C C C C C

M C

1B 1C C

2 3 4 5 6 7 8 1 U4

RL2 2 17 O

C C C C C C C C

M ULN2804 ULN2804

2B 2C C

2 3 4 5 6 7 8 1 U2 RL3 3 16 O ULN2804

3B 3C C

RL4 4 15

B B B B B B B B B B B B B B B

4B 4C ULN2804 B

2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

RL5 5 14 1

B B B B B B B

5B 5C B

2 3 4 5 6 7 8

RL6 6 13 1

B B B B B B B B

2 3 4 5 6 7 8 1 2 3 4 5 6 7 8

6B 6C 1

2 3 4 5 6 7 8

RL7 7 12 1

2 3 4 5 6 7 8 7B 7C 1

RL8 8 11

2 3 4 5 6 7 8

8B 8C 1

3 4 5 6 7

3 3 3 3 3

L L L L L

7 8 9 0 1 2 3 4

1 1 1 2 2 2 2 2

R R R R R

L L L L L L L

ULN2804 L

R R R R R R R R

5 6 7 8 9 0 1 2

2 2 2 2 2 3 3 3

L L L L L L L L

i R R R R R R R R

o 0 1 2 3 5 6

1 1 1 1 1 1

L L L L L L L

R R R R R R R +500 AC Volts +347

AC Volts

- o U8 13 9 OE Q7' INPUT VOLTAGE OUTPUT VOLTAGE 10 7 RL24 MR Q7 6 RL23 Q6 U11 5 RL22 Q5 RCK2 1 39 CO4 4 RL21 U6 PB0/T0/OC0 PA0/AD0 Q4 SCK2 2 38 CO3 RCK3 12 3 RL20 13 9 PB1/T1 PA1/AD1 ST_CP Q3 OE Q7' SER2 3 37 CO2 2 RL19 10 7 RL8 PB2/AIN0 PA2/AD2 Q2 MR Q7 RCK3 4 36 CO1 SER3 14 1 RL18 6 RL7 PB3/AIN1 PA3/AD3 DS Q1 Q6 RO3 SCK3 5 35 RO1 SCK3 11 15 RL17 5 RL6 A PB4/SS PA4/AD4 SH_CP Q0 Q5 SER3 6 34 RO2 4 RL5 9 8 7 PB5/MOSI PA5/AD5 Q4

7 33 RO3 RCK1 12 3 RL4

D E

S PB6/MISO PA6/AD6 ST_CP Q3

6 5 4 3 2 1 0 S

7 RO4 74HC595 RL3

E D S

W 8 32 2

PB7/SCK PA7/AD7 Q2

D D D D D D D E R R V V V RO2 D SER1 14 1 RL2 B DS Q1

6 5 4 10 21 D4 SCK1 11 15 RL1

3 2 1 0 9 8 7 6 5 4 3 2 1

4 PD0/RXD PC0/A8 U9 SH_CP Q0

1 1 1 1 1 11 22 D5 PD1/TXD PC1/A9 RCK4 12 23 D6 13 9 PD2/INT0 PC2/A10 OE Q7' RO1 SCK4 13 24 D7 10 7 RL32 74HC595 C PD3/INT1 PC3/A11 MR Q7

3 2 1 SER4 14 25 E 6 RL31

6 5 4 7 PD4/XCK PC4/A12 Q6

RCK5 RS RL30

D D D D 15 26 5 PD5/OC1A PC5/A13 Q5 SCK5 16 27 4 RL29 U7 PD6/WR PC6/A14 Q4 ON RO4 SER5 17 28 RCK4 12 3 RL28 13 9 D PD7/RD PC7/A15/TDI ST_CP Q3 OE Q7' 0 2 RL27 10 7 RL16 + = C Q2 MR Q7 19 31 RCK1 SER4 14 1 RL26 6 RL15

S XTAL1 PE0/ICP/INT2 DS Q1 Q6

4 3 2

1 SCK1 SCK4 RL25 RL14 R E 18 30 11 15 5 XTAL2 PE1/ALE SH_CP Q0 Q5 9 29 SER1 RCK2 4 RL13 RESET PE2/OC1B Q4 12 3 RL12 ST_CP Q3 74HC595 2 RL11 Q2 ATMEGA8515 SER2 14 1 RL10 DS Q1 SCK2 11 15 RL9

SH_CP Q0

1 2 3

4 U10

O O O O

C C C C 13 9 OE Q7' 10 7 74HC595 MR Q7 6 Q6 5 Q5 RV1 4 RL37 Q4 RCK5 12 3 RL36 POT ST_CP Q3 2 RL35 Q2 SER5 14 1 RL34 DS Q1 SCK5 11 15 RL33 SH_CP Q0 74HC595 Fig.7: Graphical user interface of the PIVD simulation.

Published By: Retrieval Number: B3930079220/2020©BEIESP Blue Eyes Intelligence Engineering DOI:10.35940/ijrte.B3930.079220 899 and Sciences Publication

Design of Programmable Inductive Voltage Divider using Minimum Inductive Elements

Performance of the reed relays and all components of the be minimized. The PIVD consists of only one-half PIVD could be verified by comparing input and output inductive elements of the conventional DIVD to achieve the voltages with the required dividing ratio. Fig. 8 shows an same resolution and obtaining the same number of the example to obtain the output ratio of 0.694. Using the PIVD output ratios using minimum inductive elements. Therefore, keypad; the input voltage of 500 V is entered and then the it is more economical to use the introduced PIVD due to its required ratio 0.694 is entered. Accordingly, the output minimum number of the used inductive elements. voltage is generated with the value of 347 V as clearly Accordingly, the electromagnetic interference, parasitic illustrated in Fig. 8. In this example, the relays no. elements and mutual inductance between its inductive 1,2,9,10,15 and 16 are set in active position to get 0.6 ratio, elements will be obviously decreased. Therefore, PIVD the relays no. 27 and 28 are set in active position to get 0.09 performance and accuracy will be improved. Traditional ratio and also relay no. 34 is in active position to get 0.004 DIVD is used in manual measurements through its dial ratio. The relays states of this numerical example are switches which confuses the user when selecting the illustrated in Fig. 7. required ratio. In addition, the switches affect the voltage

ratios stability. Whereas the introduced PIVD can be +

i controlled manually or automatically by using the relays + o system and the microcontroller. So, it can be easily used in

the automated measurement systems that have higher

E S

D E

S +500

7 6 5 4 3 2 1 0 S

E D S

7 6 5 4 3 2 1 0 S

E D S W

W +347

D D D D D D D D E R R V V V

D D D D D D D E R R V V V D AC Volts

AC Volts precision, stability with minimum effort and time. The

4 3 2 1 0 9 8 7 6 5 4 3 2 1

1 1 1 1 1

1 1 1 1

1 disadvantage of the PIVD is that all relays are connected in

7 6 5 4

D D D D

D D D

D series through a single path, which increases the effective

E S

7 6 5 4 3 2 1 0 S

E D S

D D D D D D D D E R R V V V

D D D D D D D E R R V V V D resistance. To minimize this influence, the relays will be

INPUT VOLTAGE OUTPUT VOLTAGE

4 3 2 1 0 9 8 7 6 5 4 3 2 1

1 1 1 1 1

E R R

E selected to have minimum contact resistance during the

7 6 5 4

6 5 4

7 manufacturing process of this PIVD.

D D D D

E S

7 6 5 4 3 2 1 0 S

E D S

D D D D D D D E R R V V V

4 3 2 1 0 9 8 7 6 5 4 3 2 1

1 1 1 1 1

E R R

E VI. CONCLUSION

6 5 4

Fig.8: Example7 for generating 0.694 output voltage ratio

D D D D The introduced PIVD has been designed with three stages using the simulation system.

using 17 inductors and 37 reed relays. It is controlled by

S R E only one microcontroller to obtain 10 output ratios per stage. V. ADVANTAGES OF THE PIVD OVER DIVD Then, 999 output voltage ratios can be produced by using all Design of the proposed PIVD has many advantages over the possible combinations in the range from 1×10-3 to 999×10-3. conventional design of the traditional DIVD. The transfer The necessary equations have been introduced to ratio error according to the International Electrotechnical demonstrate the performance of the presented PIVD. The Commission (IEC) 60618[12] can be expressed as in the new design technique allows the PIVD to be used in the following equation: automatic measurement systems and then obtaining their 푉표푛 푉표푎 beneficial advantages. This PIVD design has many ℯ = − (11) 푉푖푛 푉푖푎 advantages over the DIVD as decreasing the transfer ratio Where ℯ denotes the transfer ratio error, 푉푖푛 ,푉푖푎 are nominal error and using minimum inductive elements. The PIVD and actual input voltage values of each stage respectively design has been completely validated using the full and 푉표푛 , 푉표푎 are nominal and actual output voltage values of presented simulation system. The proposed simulated PIVD each stage respectively. In traditional DIVD, transfer ratios will be practically fabricated, automatically controlled and errors will be increased when using the combination reliably used in a fully automated measuring system as will between stages because the input voltage of the proceeding be presented in a future work. stage depends on the voltages across different inductive elements. Contrary in the introduced PIVD, the input REFERENCES voltage of each stage is constant while obtaining all of its 1. Grubmüller, B. Schweighofer, and H. Wegleiter, “Characterization of possible combinations because the input voltage depends on a Resistive Voltage Divider Design for Wideband Power only one constant voltage of inductive element from the Measurements”, IEEE SENSORS, pp. 1332–1335, Nov. 2014. 2. W. Wang, Y. Yang, L. Huang, and Z. Zhang, “Establishing of a 1000 previous stage. So, this inductive element can be replaced, if V Multi-Decade Inductive Voltage Divider Standard at NIM”, IEEE required, to improve the transfer ratio error which depends Access, vol. 6, pp. 58594–58599, 2018. on the input voltage of each stage as predicted from Eq. 11. 3. K. Suzuki, “A New Self-Calibration Method for a Decade Inductive Voltage Divider by Using Bifilar Windings as an Essential Standard This means that the input voltage of the second and third at Wide Frequency”, IEEE Transactions on Instrumentation and stages are controlled using only one inductive element for Measurement, vol. 58, no. 4, pp. 985–992, Apr. 2009. each. For example, the input voltage of the second stage is 4. S. Kon and T. Yamada, “Load Characteristics of Two-staged Inductive Voltage Dividers”, 29th Conference on Precision always equal to the voltage across the inductive element L5 Electromagnetic Measurements (CPEM 2014), pp. 758–759, Aug. as shown in Fig. 2. So, standard inductive elements with 2014. high accuracy should be used when the PIVD is manufactured to improve its performance by reducing the transfer ratio error. In addition, due to the constant input voltage of each stage, the divided ratio results will be near to the ideal nominal case because the accumulated errors will

Published By: Retrieval Number: B3930079220/2020©BEIESP Blue Eyes Intelligence Engineering DOI:10.35940/ijrte.B3930.079220 900 and Sciences Publication International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2277-3878, Volume-9 Issue-2, July 2020

5. B. C. Waltrip, A. D. Koffman, and S. Avramov-Zamurovic, “The Design and Self-Calibration of Inductive Voltage Dividers for an Automated Impedance Scaling Bridge”, Conference Proceedings IMTC, vol. 2, pp. 1191–1195, May 2002. 6. T. Yamada, S. Kon, and N. Sakamoto, “Evaluations of a Wideband Inductive Voltage Divider and Non-sinusoidal Power Measurement System”, Conference on Precision Electromagnetic Measurements (CPEM 2010), Daejeon, Korea (South), pp. 239–240, Jun. 2010. 7. V. L. Kim, V. N. Dainakov, and A. B. lljin, “Extending of the Frequency Range of a Multidecade Inductive Voltage Divider”, 8th Russian-Korean International Symposium on Science and Technology, KORUS, Tomsk, Russia, vol. 1, pp. 241–244, 2004. 8. D. Filipović-Grčić, B. Filipović-Grčić, and K. Capuder, “Modeling of Three-phase Autotransformer for Short-circuit Studies”, International Journal of Electrical Power & Energy Systems, vol. 56, pp. 228–234, Mar. 2014. 9. A. Dutta and S. S. Ang, “Effects of Parasitic Parameters on Electromagnetic interference of power electronic modules”, IEEE Applied Power Electronics Conference and Exposition (APEC), pp. 2706–2710, Mar. 2017. 10. J. Zhang et al., “Design and Self-calibration of Cascaded Inductive Voltage Divider with Ratio of 2n:1”, Conference on Precision Electromagnetic Measurements (CPEM 2016), pp. 1–2, Jul. 2016. 11. M. Helmy A. Raouf, A. Eliwa Gad, El-Sayed Soliman A. Said, and M. A. Elwany, “Fully Automated Inductance Measuring System Using New Fabricated Inductance Box”, MAPAN-Journal of Metrology Society of India, vol. 32, no. 3, pp. 199–205, Sep. 2017. 12. “IEC 60618:1978/AMD2:1997- Inductive Voltage Dividers | IEC Webstore.” https://webstore.iec.ch/publication/2725 (accessed Apr. 11, 2019).

AUTHORS PROFILE Ahmed Eliwa Abdo Gad, received the B. Sc. and the M. Sc., in Electronics and communications Engineering from the Faculty of Engineering, El Shorouk Academy and Al-Azhar University, Cairo, Egypt in May 2008 and February 2016 respectively. He joined the National Institute of Standards (NIS), Egypt, in 2010. In 2016 he became Assistant Researcher at the National Institute of Standards (NIS).

Mohammed Helmy Abd El-Raouf, received the B. Sc., the M. Sc., and the Ph. D. in Electrical Engineering from the Faculty of Engineering, Al- Azhar University, Cairo, Egypt in May 2001, January 2005 and 2007, respectively. In 2018 he became full Professor. He joined the National Institute of Standards (NIS), Egypt, in 2003. From 4/2010 to 4/2011 he was Post – Doctor at Korea Research Institute of Standards and Science (KRISS), Deajeon, South Korea. Since 2013, he has been a Head of Department of the Electrical Quantities Metrology at NIS. Since 2016, he is the vice chair, of the Technical Committee for Electricity and Magnetism (TC-EM) of AFRIMETS, the intra-Africa metrology system, and the Egyptian delegate to the Consultative Committee for Electricity and Magnetism (CCEM) of the International Committee for Weights and Measures (CIPM). His research interests are mainly in the electrical machines and metrology of the electrical quantities such as capacitance, inductance, resistance, impedance and AC-DC measurements. He published about 40 papers in refereed scientific journals and has 6 patents. He teaches some courses in electrical engineering.

Abd El-Hady Abd El-Azim Ammar, since 1988 he has been becoming Professor of Electronics and communications Engineering, Faculty of Engineering Al-Azhar University, Cairo, Egypt. His research activities are within digital communications, mobile communication and digital signal processing.

Published By: Retrieval Number: B3930079220/2020©BEIESP Blue Eyes Intelligence Engineering DOI:10.35940/ijrte.B3930.079220 901 and Sciences Publication