Попробовать с кавычками:
Код:
$S = Get-Date -UFormat "%d_%m_%Y_%H-%M"
$p = 'DESIGNER','/S\"pab-asu-1c8.puma.com\zarpnew\"','/N\"backup\"','/P\"000000\"','/DisableStartupMessages',"/Out\""E:\temp\log\ZUP_Log_$S.log\""",'-NoT_runcate',"/DumpIB\""E:\temp\ZUP_$S.dt\"""
$1c8 ="C:\Program Files (x86)\1cv82\common\1cestart.exe"
&$1c8 $p
