Temperature Control - Siemens Maxum II Manual

Figure 3-2
See also
Safety Systems - Purging (Page 17)
3.2.2

Temperature Control

As mentioned in section 3.1, the temperature of the oven is controlled via an RTD sensor. The
temperature of the air itself is controlled via two independent sensors which work with the two
set point resistors mentioned in section 3.1 to ensure that all temperatures remain below
possible ignition limits. The limits set by these set point resistors determine the "T-rating" of
the entire analyzer in any given situation. The sensors are located inside the heater assembly
near where the air exits the assembly.
The first sensor is a "temperature limit" sensor that detects whether the air has reached a
certain limit based on the applicable T-rating. If this temperature limit is reached as indicated
by this sensor, then the power to the heater is cut until the temperature falls below the limit
point. If the primary sensor should fail, a second "Over Temperature" sensor will activate at a
slightly higher temperature. If this happens, then the power to the oven heater is interrupted.
Because this sensor should not activate unless there is a mechanical failure of the first sensor,
the power to the heater cannot be reactivated without user intervention.
See also
General Oven Information (Page 35)
Explosion Protection Safety Standards
Manual, August 2017, A5E02220442001 Rev 8
3.2 Isothermal Air Bath Oven Heater System (Single and Split)
Timing Coil for Pressure Switch
Safety Systems - Oven
37