2.5.4
Intrinsically-Safe Thermal Conductivity DPM (IS-TCD3)
Overview
Output signals from Thermal Conductivity Detector (TCD) in the Modular Oven are input to the
associated Detector Personality Module (DPM). The DPM is mounted inside the Electronics
Enclosure (EC) on the floor of the compartment. The DPM digitizes the incoming analog signal
and then passes the data to the SYSCON via an I
2
C port. The resulting data is then processed
by the Embedded SNE software. Results can then be viewed on the maintenance panel or the
workstation.
TCD Beads
(thermistor)
IS-TCD
DPM
(A/D)
PECM
SYSCON
Color
Touch
Display
GCP
Analog
I
2
C
I
2
C
Network
Figure 2-32 Thermal Conductivity Detector Signal Path
The IS-TCD3 DPM is an enclosed unit that is not field repairable. Opening the case may violate
the safety protection of the device. Service is limited to replacement of the entire DPM.
Part Number
The IS-TCD3 DPM (part number A5E02645923001) is shipped with current analyzers. It can
be used as a replacement part for earlier DPMs in Maxum I analyzers using an adapter, part
number A5E34938550001.
Intrinsic Safety
The intrinsic safety feature of this module is only used in the Maxum II Modular Oven model.
The following two paragraphs apply only if this feature is used.
The TCD DPM in the Maxum II, as well as the actual detector controlled by the TCD, is
protected by intrinsic safety. Intrinsic safety is a method of protection where a circuit is designed
such that it will not create a spark or other condition capable of causing ignition of flammable
vapors or gases, even under fault conditions. Various circuits in the Maxum analyzer use this
form of protection, including the IS-TCD3.
Note
To preserve the intrinsically safe design protection of the IS-TCD3, certain measures are
required. Failure to adhere to all requirements for use of the IS-TCD3 in the Maxum
II could
violate the safety protections of the analyzer. See the Maxum II Explosion Protection Safety
Standards Manual (A5E02220442001) for more information on the safe use of intrinsically safe
circuitry in the Maxum II.Maxum II Explosion Protection Safety Standards Manual
(A5E02220442001) for more information on the safe use of intrinsically safe circuitry in the
Maxum II.
Electronic Compartment Component Descriptions and Maintenance Procedures
2.5 Detector Personality Modules
Maxum II Reference Manual
68
Manual, 7/2017, 2000596-001
