Set site collection admin for all sites using Powershell

Powershell script to set Site Collection Administrator for all sites in a web application:

$scadmin = "domain\user"                        # Admin Domain\account
$Sites = Get-SPsite
 
foreach ($site in $Sites) {
    Set-SPSite -Identity $site -SecondaryOwnerAlias $scadmin
    }

Make sure you run this using SharePoint Management Shell and using Run as Administrator