Pemissible number of starts-stops depends upon
actuator size & speed. The details are available
Open Close Duty
Regulating / Modulating Duty
Short Time and Intermittent Duty IS 12824
Functions
Typical Characteristics of
OPEN-CLOSE DUTY
Typical Characteristics of
Regulating / Modulating Duty
Short time Duty S2 Intermittent Duty S4
S2-15min.
The characteristic feature of this actuator is
open loop. The normal valve positions in
OPEN-CLOSE Duty are end positions OPEN
and CLOSED. After receiving command, the
actuator operates the valve to one of the end
positions or if necessary to a preset
intermediate position. The valves are operated
relatively seldom, the time intervals can span
Auma multi-turn actuators type SA for open
close service are rated for short time duty
between a few minutes to several months.
in Data Sheets.
Operation at constant load during a given
time, less than that required to reach thermal
equilibrium, followed by a rest and de-
energized period of sufficient duration to re-
The duration of short time is limited to 15, 30
or 60 min.
o
establish machine temperatures within 2 C.
The characteristic feature of this actuator is
closed loop in which input command signal to
actuator is directly influenced by the flow
through the valve. Regulating / Modulating
duty actuator SAR operates between two set
bands between open-close positions depending
upon actual valve position and feedback signal.
The motors of these actuators are rated for
intermittent duty S4-25%. The mechanical
components and motor are designed to withstand
a large number of operations required for
modulating applications.
8
A sequence of identical duty cycles, each cycle
including a significant period of starting, a period
of operation at constant load and a rest and de-
energized period. These periods being too short
to attain thermal equilibrium during one duty
The relative on time at S4-25% is limited to
25% of the cycle time.
cycle.
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