Notable Features Of The Vsm Oven Option; Theory Of Operation; Figure 1-1. Operating Principle For The Vsm Oven Option - Quantum Design CM-C User Manual

Section 1.4

Theory of Operation

Ease of use is another advantage of the Quantum Design VSM Oven option—it uses the same
VSM detection coilset as the standard (low temperature) mode of the VSM option. To change
from the standard VSM mode to the VSM Oven mode, you simply insert a different sample rod
into the VSM.
1.3

Notable Features of the VSM Oven Option

Figure 1-1 illustrates the hardware and functional connections necessary for operating the VSM
Oven. A new CAN module, the Model CM-C VSM Oven module, has been introduced to handle
the temperature control of the VSM Oven heater stick. This module plugs into the Model 1000
Modular Control System, which communicates with the PC via the CAN network cable. The
oven-control cable plugs into the front panel of the oven-control module. This cable passes heater
power and temperature readback information to the heater stick via the electrical feedthrough on
the wired access port and the wired oven sample rod.
1.4 Theory of Operation
The platinum heater is driven synchronously to the power line frequency (50 Hz or 60 Hz,
depending on country and region) with a sinusoidal excitation. Magnetic feedthrough from the
heater currents into the VSM detection coilset is minimized by patterning the heater
noninductively and by operating at line frequency, where the VSM detection circuitry can easily
reject the signal. The thermocouple voltage is monitored constantly by a sensitive low-drift DC
microvolt preamp in the VSM Oven module. The thermocouple junction is located in the middle
of the heater region of the stick, and the thermocouple wires terminate at the connector at the top
of the stick. Note that the thermocouple table is referenced to a cold junction at 273 K (0 ºC).
Also located at the connector is a negative temperature coefficient thermistor that corrects for the
1-2

Figure 1-1. Operating principle for the VSM Oven option

VSM Oven Option User's Manual, Rev. A3
May 2011
Chapter 1
Introduction to the VSM Oven Option
Quantum Design