IM-P402-84 AB Issue 6
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6. Commissioning
The LC2400 has two channels; 'steam' and 'water', each channel consisting of a 4 -20 mA input
and a scaled output signal. To aid commissioning, each channel has a test input, which allows
measurement of the 4 - 20 mA signal without breaking the loop. See figure 5. The 'steam' channel
also has a range link, which selects one of two ranges to suit the anticipated rise in water levels.
In most cases, the link is fitted. See 'Steam flowmeter input' and figures 6 and 7.
Calibration is carried out by adjusting the 'steam' potentiometer on the LC2400. This raises the
control set point to match the rise in boiler water level at maximum steam demand.
For three element control using the LC2200 controller, the 'water' potentiometer is set to suit the
water flowmeter range.
Preferred commissioning method Level probe input-
- Adjust the 'steam' potentiometer on the LC2400 to the zero position.
- Set the boiler water level (gauge glass) to the desired normal water level (set point).
- Adjust the LC2200 (or LC2300) set point potentiometer until the >50 % green LED just lights.
- Set the boiler water level to either the top or the bottom of the desired proportional band
(valve fully closed /fully open position), whichever is most convenient.
- Adjust the LC2200 (or LC2300) proportional band potentiometer until
the >100 % /<0 % amber LED just lights
The IM for the LC2300 gives further details of this procedure.
Steam flowmeter input
- Fit a wire link between terminals 4 and 5 of the LC2400.
- Alter the boiler water to the level anticipated when the steam demand is 100 %, i.e.
maximum steam flow.
- Adjust /program the steam flowmeter to output a 4 -20 mA signal representing 75 % of maximum
steam flow (usually 16 mA). See note below.
- Adjust the 'steam' potentiometer on the LC2400 until the green > 50% LED on the LC2200 /
LC2300 just extinguishes.
- Alter the water level to the set point (at zero steam flow).
- Adjust /program the steam flowmeter to output a signal representing 0 % of steam flow (4 mA).
- Adjust the 'set point' potentiometer on the LC2200 / LC2300 until the green LED just lights.
Notes: If the green LED does not extinguish then remove the range link from terminals 4 and
5 then readjust the 'steam' potentiometer.
In use, the steam flowmeter output is 4 mA at zero steam flow, and 20 mA at maximum steam
flow. However, when we adjusted the LC2200/ LC2300 set point the steam input was
equivalent to zero output from the steam meter, not 4 mA. The steam flowmeter was set at 75%
output to compensate for this.