Automatic Purge Unit - Siemens Maxum Edition II Installation Manual

Installations without APU
For analyzers not equipped with an Automatic Purge Unit (APU), connect the all signal cables
to the chromatograph via the metal cable glands. This is the standard configuration for Maxum
II analyzers in CE areas.
Installations with APU
For analyzers equipped with an APU (optional configuration) connect all signal cables
that cannot accidentally be energized from outside (e.g. relay contacts), to the chromatograph
via the metal cable glands. For analyzers equipped with an APU connect all signal cables
that can accidentally be energized from outside (e.g. Ready, RS485, Ethernet), to the signal-
disconnector unit relay boxes attached to the left side of the analyzer.
Figure 3-12 APU signal disconnector units
3.5.5

Automatic Purge Unit

The Automatic Purge Unit (APU) is an optional device applicable to some CE installations. It is
designed to monitor and control the purge system of the Maxum II analyzer. When purge
pressure is lost, the APU will disable power to the analyzer and disconnect all possible sources
of external voltage via external relay boxes (disconnector units) mounted to the outside of the
analyzer.
Some examples of APU connections are shown in the Power Connections (Page 21). section.
More information on APU operation is presented in the MAXUM II Explosion Protection Safety
Standards Manual (https://support.industry.siemens.com/cs/document/42017542/)
Installation Manual
Installation Manual, 12/2019, 2000595 Rev 1
Installation Steps
3.5 Cable Connections
27