
LAUDA Ultra-Thermostats
UB 20(-D), UB 25, UB 50, UB 30, UB 40
UB 20 F, UB 20 J, UB 30 J, UB 40 J, UB 65 J
UB 20 JL, UB 30 JL, UB 40 JL
YATE0013 / 10.04.02
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The digitizing of the Pt 100 resistance signal is performed in the microprocessor by
continuous comparison with precision resistors. The secondary control using a modified
PID control algorithm is purely digital. The tubular heater for the heating of the bath is
then operated electronically using a triac with burst firing action.
The tubular heaters have a surface loading of approx. 6 W/cm
2
.
3.6
Mains supply output 34 H
The 230 V supply voltage is available at the socket 34 H at the back in normal operation
and with the unit switched on. The maximum current which can be drawn there is 2 A.
In case of a fault this supply is switched off. This output can be used e.g. to connect a
through-flow chiller or a non-return fitting (Cat. No. UD 125).
Suitable mating plug
Cat. No. EQS 045
3.7 Controlled
cooling
The units are equipped for controlled cooling to operate a solenoid valve which controls
the cooling water flow. This provides fully automatic cooling (20...100°C). It ensures
faster heating up (compared to continuous cooling), greatly reduced water consumption
and improved temperature control during heat dissipation since the heater does not
operate against the cooling action.
Voltage output (19 H) 230 V; 50/60 Hz max. 0.2 A.
Solenoid valve for cooling water control
Cat. No. UD 085
4
Safety devices and warning notes
4.1 Safety
functions
The built-in overtemperature limiter can be set over the complete operating temperature
range.
The bath temperature is measured by a separate Pt 100 resistance sensor (T
Si
) and
processed by a separate analogue/digital converter. This measured value is compared
with the measured value of the bath temperature probe (T
i
) continuously. If the
measurements differ by more than +15 K the thermostat switches off as in the case of a
low-level or overtemperature fault.
The function of the microprocessor is monitored by an integrated watchdog circuit and
an additional counter which operates similarly to a normal watchdog circuit but is also
capable of switching off the unit in case of a strobe failure.
When the set overtemperature switch-off point (T
O
) is exceeded the unit switches off
permanently on all poles.
A float switch with magnetic coupling acts as a low-level cut-out and also switches off
the unit (pump and heater) permanently on all poles.