Fig. 3: relative values
The main setpoint S1 and the point of ramp
employment are linked as difference with one
another. This difference can take positive or
negative values, i.e. starting point for the
ramp can be above the setpoint at cooling
function or below the setpoint at heating
function, and automatically runs along with
adjustments of the desired value.
Fig. 4: absolute values
Main setpoint S1 and ramp employment point
are independent from each other
P12: Ramp gradient
The ramp gradient sets the degree applied to change the (internal) setpoint in a ramp phase.
P19: Key-lock
The key-lock allows blocking of the control keys. In locked condition parameter adjustments with
keys is not possible. At the attempt to adjust the parameters despite key-lock the message "==="
appears in the display.
P30: Lower alarm value
P31: Upper alarm value
The exit alarm is a boundary alarm or a range alarm with symmetrical hysteresis (see P32). Both at
the boundary alarm and the range alarm, limit values can be relative, i.e. going along with the
setpoint, or absolute, i.e. independent of the setpoint. The operation mode is set with parameter
A30. If, in case of boundary alarm and only one switching point is required the not used second
switching point should be adjusted to a value above or below the operating range of the controller.
Boundary alarm function (see fig. 5):
The alarm contact is closed if the process
temperature is above the upper or below the
lower boundary value.
Fig. 5: Boundary alarm, rel. boundaries
Range alarm function (see fig. 6):
Opposite switching behaviour to the boundary
value alarm. The alarm contact is closed if
the actual value remains between the
boundary values.
Fig 6: Range alarm, abs. boundaries
P32: Hysteresis alarm circuit
Hysteresis is set symmetrical at the adjusted limit value, i.e. half of the hysteresis’ value is effective
below and half of the value above the switching point
Summary of Contents for ST70-31.03
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