A23: Alarm suppression after "Power-On"
This parameter allows a switching-on delay of the alarm contact after switching on the mains
voltage. This suppression corresponds with the time set here. The suppression is only active when
the alarm is activated the first time. The suppression not to the contacts K1 and K2.
A30: Function alarm exit
The alarm exit evaluates an upper and a lower limit value (see parameters P30 and P31), whereas
a selection is possible as to whether the alarm is active if the temperature lies within these two
limits (range alarm), or whether the alarm is released if the temperature lies beyond them
(boundary alarm). In the case of sensor error, the alarm is activated as follows: at range alarm
function the alarm relay is off and at boundary alarm function the alarm relay is on. In case of
parameter memory error all contacts will be switched off.
A31: Special function at boundary alarm
6 different special functions can be selected in the case of an alarm. At functions 1-3 the buzzer
can not be switched off, therefore the alarm terminates as soon as the error is eliminated. At
functions 4-6 it is possible to switch off the buzzer, whereas a repetition after two different time
intervals is possible.
A32: Special function of upper display
A33: Special function of lower display
This parameter permits a permanent special display in the upper or lower display. It is possible to
indicate the setpoint, formed by reference variable and the given offset temperature, the offset
temperature (if differential control) or the actual difference value. In this case, the usually indicated
following or leading value is not available in the first parameter level.
Note: If offset temperature is selected and there is no differential control, the following value is
indicated in the upper display and the lower display is off. The lower display stays off, if no special
function is selected or if there is no differential control.
A34: Indication with function key 1
If activated with b1=2, function key 1 can be parametered to indicate the leading value, the offset
temperature or the actual difference. This feature is important especially for units with only one
display.
A35: Adjustment of setpoint S1‘ (not available on all types of controllers)
The functions of this parameter are only effective if there is a switching input E1 available. By
closing switching input E1, setpoint S1 can be switched to a setpoint S1’. Setpoint S1’ can be
either added to the difference value S1 (S1+S1’) or an independent, freely adjustable, difference
value or an independent, freely adjustable setpoint. In case of a freely adjustable setpoint the
leading value has no more influence on the setpoint end the respective sensor can be
disconnected; an error message will be suppressed. The lower display remains deactivated as
long as there is no special function set with parameter A33.
The setpoint S1’ can only be indicated and adjusted by means of the SET key if input E1 is closed.
A40: Hysteresis mode contact K1
A41: Hysteresis mode contact K2
These parameters allow selection as to whether the hysteresis values which are adjustable with P2
and P3, are set symmetrically or one-sided at the respective switching point. At symmetrical
hysteresis, half of the hysteresis’ value is effective below and half of the value above the switching
point. The one-sided hysteresis works downward with heating contact and upward with cooling
contact. The hysteresis is only effective in case of thermostatic control. With PID characteristics the
hysteresis has no effect.
A42: Hysteresis mode alarm contact
These parameters allow selection as to whether the hysteresis value which is adjustable with P32,
is set symmetrically or one-sided at the respective switching point. At symmetrical hysteresis, half
Summary of Contents for ST48-WHDVM.04
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