80
Glossary
continued
Switching hysteresis Hyst (conductivity control)
If X
p
= 0 is set, the controller is configured as a 2-position controller, which means that the valve will
open if there is a position deviation (X > w). The conductivity must then decrease until a new valve
that is lower than the setpoint minus the adjusted hysteresis is reached. Once this value is reached the
valve will be motored into the operating position.
Switching times (conductivity and capacitance level control)
Individual time delays for energising and de-energising can be set for each of the four output relays.
Standby mode (conductivity control)
To avoid loss of water, the continuous blowdown control and the program-controlled intermittent boiler
blowdown (if activated) can be deactivated during stand-by operation or when the burner is switched
off. An external control command will be triggered and, as a result, the continuous blowdown valve will
be CLOSED. During stand-by operation the MIN/MAX limits and the monitoring function remain active.
After the equipment switches back to normal operation, the continuous blowdown valve is motored
into the OPERATING position. In addition an intermittent blowdown pulse is triggered (provided that
automatic intermittent boiler blowdown has been activated and an interval period and pulse duration
have been set).
Temperature compensation (conductivity control)
The electrical conductivity of water changes as the temperature falls or rises. To obtain meaningful
readings it is therefore necessary that the measurements are based on the reference temperature of
25°C and that the measured conductivity values are corrected by the temperature coefficient factor
α
(Tk).
For automatic temperature compensation the following three settings are available: TK Linear, TK Norm
or TK Auto.
TK (Linear)
To ensure that the readings are based on 25°C, set the TK value between 0 and 3.0 %/°C (default set-
ting 2.1 %/°C). This setting permits the linear temperature compensation of the measured value over
the whole measuring range. This method is usually applied for steam boilers operating at a constant
service pressure. After the TK is set and the service pressure is reached, use a calibrated conductiv-
ity meter to measure the conductivity of the boiler water and compare the reading with the indicated
conductivity value. If the reading differs from the indicated conductivity, change the TK setting until
they tally.
TK (Norm)
Since conductivity is not a linear function of temperature over a larger temperature range, various con-
ditioning agents and different basic conductivities were used in order to ascertain empirical conductiv-
ity/temperature curves. These curves are stored as standard curves and can be used for temperature
compensation. TK (NORM) is suitable for steam boilers operating with variable pressure, which means
that the boiler does not have a fixed working pressure (e.g. low load 10 bar, full load 15 bar).
TK (Auto)
For this method a characteristic conductivity/temperature curve of the plant (Auto curve) is used for
temperature compensation. However, a characteristic Auto curve must be recorded first. For this pur-
pose turn the navigation wheel at TK (AUTO) to Start and then press the navigation wheel in order to
start recording the curve. Now increase the steam boiler to the highest operating pressure. During the
heating process, temperature and conductivity values are recorded at every 10 °C above 100 °C and
the current temperature is shown. After having recorded 25 values or if STOP is selected, the equip-
ment stops recording and saves the Auto curve. The TK (AUTO) process is suitable for steam boilers
operating with variable pressure.
When the compensation is switched OFF the absolute conductivity is indicated.
Summary of Contents for SPECTORcontrol
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