810-1734-00 Rev A GAS-Guard 8 and GAS-Guard 3 Operations and Maintenance Guide
7
of
18
Gassing Transformers which have been degassed:
Set the caution level to 50% and the alarm level to 100% of the low-end CAUTION ppm limits
proposed by IEEE PC57.104 Draft 11, published April 21, 2004; except acetylene, as noted below.
Gas
Caution PPM
Alarm PPM
Notes:
Hydrogen 50
100
Methane 60 120
Acetylene
2
5
Per Draft 11
Ethylene 25
50
Ethane 33 65
Carbon Monoxide
175
350
Carbon Dioxide
1750
3500
Oxygen
b10%
B20%
above initial measured PPM
Table 4: Recommended caution/alarm settings for gassing transformers after degassing
Transformers with an unstable gassing history which have not been
degassed:
There are no recommendations possible for transformers in this category. In order to establish the
caution and alarm levels, allow the GAS-Guard to run for thirty (30) days to establish gassing trends
and baseline measurements. After this data has been collected, you should consult with Siemens
(
) to determine the appropriate caution and alarm settings for the transformer.
Viewing GAS-Guard Data
The GAS-Guard data can be viewed using the supplied GAS-Guard View software or the optional
Serveron Monitoring Service Client software. A copy of the GAS-Guard View software and user’s
manual can be found on the CD that shipped with the GAS-Guard. Alternatively, the GAS-Guard can
present data to SCADA systems using DNP3 or Modbus protocols. Please contact a Siemens
representative for further information regarding the Serveron Monitoring Service or to integrate the
GAS-Guard with a SCADA system