Example how to query the downtime of a device which has an alert configuration on the state of the machine (state 0/1):

select element_name, sum(downtime) downtime from (
select e.element_name,
h.ts,
h.VALUE_NUMBER,
h.direction,
case
when h.DIRECTION = 0 then
CAST((h.ts + 0) - ((lag(h.ts, 1, h.ts) OVER(ORDER BY ts)) + 0) AS FLOAT)*24*60*60
else
null
end as downtime
from elements e
join alerthistory h
on e.element_id = h.ELEMENT_ID
where e.element_name like
'Device_%.Status'
and ts between to_date('01.07.2014','DD.MM.YYYY') and to_date('31.07.2014','DD.MM.YYYY')
) group by element_name