[Tex/LaTex] How to set the chapter title in center of the page

Question

I want to set (Chapter 1 Introduction) and (Chapter 2 Protective Relay) only in the center of the page, I try to use \vspace*{} and \vfill but unfortuntly It isn't work, My code is:

\documentclass{report}

\usepackage{sectsty}
\chapterfont{\huge\sc\centering}
\chaptertitlefont{\centering}
\begin{document}

\chapter*{List of Abbreviations}
test
\newpage
\chapter*{List of Tables}
test test test test test test test test test test test test test test test test test test test test test test test test
\newpage
\chapter{Introduction}
\newpage
test test test test test test test test test test test test test test test test test test test test test test test test
\chapter{Protective Relays}
\newpage
test test test test test test test test test test test test test test test test test test test test test test test test
\end{document} 

Answer 1

I have put (Chapter 1 Introduction) and (Chapter 2 Protective Relay) only in the center of the page. After you must use \textsc instead of \sc. I hope that I solved your problem.

\documentclass{report}
\usepackage{sectsty}
\usepackage[pagestyles]{titlesec}
\titleformat{\chapter}[display]
{\normalfont\huge\sc\centering}{\vspace{5cm}\centering\chaptertitlename \thechapter}{20pt}{\Huge}
\titlespacing*{\chapter}
{0pt}{50pt}{10pt}



\begin{document}

\chapter*{List of Abbreviations}
test
\newpage


\chapter*{List of Tables}
test test test test test test test test test test test test test test test test test test test test test test test test
\newpage
\chapter{Introduction}
\newpage
test test test test test test test test test test test test test test test test test test test test test test test test
\chapter{Protective Relays}
\newpage
test test test test test test test test test test test test test test test test test test test test test test test test
\end{document}