wtw 115 VAC, Operating Manual

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Cleaning Air Box Operation
ba75731e04 12/2013
4 - 1
4 Operation
4.1 Operating modes
Fig. 4-1 Pulse operation with the Cleaning Air Box
The Cleaning Air Box is designed for discontinuous operation. After a certain
pump time
t1 ("cleaning duration") a stoppage t2 that lasts at least five times as
long as the cleaning duration must follow (for example 2 min On, 10 min Off).
The maximum allowed cleaning duration is 300 s.
NOTE
The Cleaning Air Box is not suitable for continuous operation. Continuos opera-
tion can lead to an automatic switch-off due to excessive heat.
Control relays All relays of WTW instruments (e.g.
IQ S
ENSOR
N
ET
or measuring transmitters
of the 170 and 296 series) can be configured for activation of the Cleaning Air
Box. The maximum allowed cleaning duration for the Cleaning Air Box is auto-
matically observed with these instruments. More detailed information is given in
the instruments' operating manuals.
NOTE
The control relay should work exclusively as a closer to avoid continuous oper-
ation of the Cleaning Air Box in the case of a power failure at the measuring sys-
tem. All relays that can be configured for cleaning purposes of WTW instruments
are permanently set to "Closer".
Cleaning
Air Box
Off
On
t1
t2 = min. 5 x t1
t1 = max. 300 s
t1 t1
Time
t2 t2