Disable Sandbox Model for Word Automation Services using PowerShell

clear
Remove-PSSnapin Microsoft.SharePoint.Powershell -ErrorAction SilentlyContinue
Add-PSSnapin Microsoft.SharePoint.Powershell

$sp = Get-SPServiceApplication | where {$_.TypeName.Equals("Word Automation Services")}  
$sp.DisableSandbox = $true
$sp.Update()