Crowcon Crowcon Gasmaster, Installation, Operation And Maintenance Manual, Page: 18 / 48

Installation Crowcon Gasmaster
14
No detectors!
Please configure
To configure your system go to page 25.
2.11 Battery back-up times
Gasmaster is fitted with 1.2 Ah batteries to
provide continued operation in the event of a
power loss. Examples of typical back-up times are
provided below for a system in a non-alarm state,
relays set as de-energised and with the 4-20mA
outputs unused (system current consumption
without detectors is approximately 50mA):
Gasmaster 1
with a toxic gas detector (2-wire): 21 hours
Gasmaster 1
with an oxygen detector (2-wire): 16 hours
Gasmaster 1
with a mV pellistor flammable gas detector:
12 hours
Gasmaster 4
with four toxic gas detectors (2-wire): 10
hours
Gasmaster 4
with four oxygen detectors (2-wire): 4 hours
Gasmaster 4
with four mV pellistor flammable gas
detectors: 3 hours
Gasmaster incorporates protection to prevent
the internal batteries being damaged by being
deeply discharged. When operating from internal
batteries, Gasmaster will display a "Warning -
battery low" fault message when the battery
voltage drops to 22 V. When the voltage drops
to approximately 20 V, the batteries will be auto-
matically disconnected. The batteries will only be
re-connected when the external power supply is
re-instated, and will take approximately 18 hours
to fully re-charge.
Note:
The internal batteries may not be charged
efficiently when Gasmaster is powered from an
external dc supply, and therefore the back-up
function may not work if the external supply fails
Please contact Crowcon for further advice.
2.12 Commissioning
Note: it is strongly recommended that persons
intending to commission a Gasmaster system first
read and understand the Operating instructions
provided in section
III. Operation.
When all field devices have been connected and
powered-up, commissioning can commence. Gas
detectors should be calibrated according to their
instructions, fire detectors should be tested using
appropriate tools.
Alarms should be simulated and actions noted to
ensure that the system operates as intended. All
warning devices should be checked, and inter-
faces with auxiliary equipment should also be
verified. The
Test and View menu's are provided
for this purpose (see page 30 and on page 27).
2.12.1. Commissioning mV pellistor
detectors
It is essential for these types of detectors that the
correct ‘head voltage’ and balance is set before
attempting to zero and calibrate the sensor.
To set the head voltage, measure the voltage
across the ‘+’ and ‘-‘ terminals at the detector and
adjust the ‘HEAD VOLTAGE’ potentiometer on the
appropriate Gasmaster input module. Check the
detector instructions for voltage settings: 2 V dc is
typical for an Xgard Type 3 or 4 detector.
Allow the sensor to warm-up for 1 hour and then
adjust the amplifier balance as follows: connect a
meter set in the dc mV range to test-points TP12
and TP13 on the Gasmaster mV pellistor input
module. Adjust the ‘BALANCE’ potentiometer
until the meter reads ‘300 mV'.
The sensor is now ready for zeroing (having
first checked no flammable gas is present) and
calibration.
Note: for some gas types or pellistor types in may be
necessary to change amplifier gain settings. These
procedures are explained on technical note FGM3-
001 which can be downloaded from the Partners
section of the Crowcon website. Alternatively con-
tact customersupport@crowcon.com.