Display Circuit Board; Pellistor Input Board (Optional) - Dräger PEX 3000 Instructions For Use Manual

Display circuit board

The display board comprises of a large LCD, LED's, reset switch, piezo horn and
associated electronics. The display board connects to the main circuit board via a
short ribbon cable.
A small DIL switch allows the full-scale deflection of the display board to be set and
the TWA computation to be activated (according to software version). The reset
switch will reset/accept triggered alarms and reset the TWA value (if applicable).
Display board (4208581) with Rev 1.00 software does not allow a TWA alarm, just a
rolling 8 hour calculation.
Display board (4208636) with Rev 2.00 software allows a TWA value to be
computated and a TWA alarm to be set.
The LCD display shows different statuses. These are
-Ur- Under-range
-Or- Over-range
- 2.5 Negative gas reading below zero and above under-range
10.7 True gas reading (typical)
The -OR- display is latching. The display can only be reset via the reset switch when
the input is below full scale.

Pellistor input board (Optional)

The Pellistor board allows for the direct connection of a Pellistor measuring head. The
Pellistor board connects to SK2. Three potentiometers allow for the Pellistor drive
current to be set and the zero/span points to be adjusted.
A small DIL switch allows for the sensitivity of the Pellistor input to be selected and
the setting of two drive current ranges.
The maximum loop resistance that the Pellistor board can drive is 14 ohms (7 ohms
per core) for the Draeger Pellistor at 270mA. The maximum cable lengths for 1.5mm
2
and 2.5mm are
2
1.5mm max cable length = 250 metres
2
2.5mm max cable length = 400 metres
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