SOURCE

<svg  width="600" height="600" >
    
      <circle cx="80"cy="80"r="50"fill="none" stroke-width="3" stroke="gray" />
    <circle cx="80"cy="80"r="50"fill="none" transform-origin="50% 50%" stroke-width="3" class="yuan" />
</svg>

@keyframes asd{
    0%{ 
      transform:rotate(0deg);
    }
    100%{
     transform:rotate(360deg);
    }
}
.yuan{
    stroke: red;
    transform-box: fill-boX;
    stroke-dasharray:78 236;
    animation:asd 1s infinite linear ;
    
}