Spirax Sarco LC2400 User manual

IM-P402-84 AB Issue 6 1
LC2400 Controller
Installation and Maintenance Instructions
IM-P402-84
AB Issue 6
4025950/6
Printed in the UK © Copyright 1999
1. Safety
2. Application
3. Description
4. Installation
5. Wiring
6. Commissioning
7. Calibration notes
8. Maintenance
9. Fault finding

IM-P402-84 AB Issue 62
Your attention is drawn to Safety Information Leaflet IM-GCM-10.
1. Safety
2. Application
Whenalargesteamdemandismadeofaboiler,
the pressure will drop, and large bubbles of
steam will be formed in the water. This causes
the water level to rise, and can cause the
feedwater valve to close. Although the level of
water has increased, the mass of water will be
decreasing, a situation which actually
requires the feedwater valve to be opening. A
two element control system (probe/level
controller and steam flowmeter), uses the
output from the steam flowmeter to move the
set point of the level controller.
This compensates for the tendency of the
feedwater valve to close when the steam
demand is high. Under certain conditions
where the boiler feedwater pressure varies
considerably, perhaps due to other boilers
drawing water, three element control provides
even closer compensation.
A three element control system uses an
additional input from a water flowmeter to
compensate for any variations in feedwater
pressure.
3. Description
The Spirax Sarco LC2400 is used to connect
alevelcontrollertothe4-20mAoutputsignals
from the steam flowmeter and (where fitted),
the water flowmeter. The controller can be an
LC2200(foranelectricallyactuatedfeedvalve),
or an LC2300 (for a pneumatically actuated
valve). The LC2400 has 'steam' and 'water'
potentiometers which are used to scale the
outputsofthemeters.AgreenLEDnexttoeach
potentiometerindicatesthatasignalispresent.
4. Installation
Warning
Isolatethemainssupplybeforeunplugging
LC2200 or LC2300 controllers since live
terminals at mains voltage will be exposed
in the controller base.
Controllersshould beinstalled inan enclosure
or control panel to provide environmental
protection.
CAUTION: Allow 15mm spacing between
adjacent units for air circulation.
Spirax Sarco can provide suitable enclosures.
The controller may be mounted on a 'top hat'
section DIN rail using the mounting clip
provided, or the clip may be removed and the
controller base screwed direct to a chassis
plate.

IM-P402-84 AB Issue 6 3
5. Wiring
Screened cable is recommended for the LC2400 wiring. The LC2400 is powered by the current
loops(4-20mA)andsoneedsnoseparatepowersupply.Figures1to4,pages4,5,6,and7,show
the wiring connections for various applications.
Clamping screw
Steampotentiometer
Waterpotentiometer
Clamping screw
Green LED's

IM-P402-84 AB Issue 64
Note on 4-20 mA loops:
Steam and water meter inputs (terminals
3 and 10) are earthed via the level probe.
Ensure any equipment connected to the
loop will operate with these terminals
grounded (earthed).
Steam meter
LC2400
Level controller LC2200
Live
Alarm
relay
Neutral
For range link see
commissioning
instructions
Range
link
Test
Control
relay
Neutral
Open
Close
Feedback
input
Feedback
potentiometer
1 000 ohms
Note:
Otheractuators
may have different
connections
Capacitance
probe
IN1
IN2
IN3
Connections to
EL5600 series
actuators
For link position
and sensitivity see
Preamplifier IM
2
3
4
5
6
78
9
1
10
11
12
2
4
1
2
3
1
4-20 mA
current
loop 4-20 mA
input
Set point output
+
-
1
2
3
4
5
6
7
+
8
9
10
11
12 13
16
15
14
17
18
19
+
14
15
16
LC2200
Levelcontroller
LC2400
Steam meter
Level
probe
Steam
Motorisedvalve
Fig. 1 Two element level control
with electric valve
Make-up water
X5
X4

IM-P402-84 AB Issue 6 5
Note on 4-20 mA loops:
Steam and water meter inputs (terminals
3 and 10) are earthed via the level probe.
Ensure any equipment connected to the
loop will operate with these terminals
grounded (earthed).
Make-up water
LC2400
Steam meter
Steam
Level
probe
LC2300
Levelcontroller
Fig. 2 Two element level control
with pneumatic valve
Pneumatic
valve with
positioner
Steam meter
LC2400
Level controller LC2300
Live
For range link see
commissioning
instructions
Range
link
Test Neutral
Capacitance
Probe
IN2
For link position
and sensitivity see
Preamplifier IM
2
3
4
5
6
78
9
1
10
11
12
4-20 mA
current
loop 4-20 mA
input
+
-
1
2
3
4
5
6
7
8
9
10
11
12
+
4-20 mA
output -
+
-
IN1
4-20 mA
current
input
+
-
2
3
1
Electropneumatic
positioneronvalve
Live
Neutral
Test
Set point output

IM-P402-84 AB Issue 66
Note on 4-20 mA loops:
Steam and water meter inputs (terminals
3 and 10) are earthed via the level probe.
Ensure any equipment connected to the
loop will operate with these terminals
grounded (earthed).
Steam meter
LC2400
Level controller LC2200
Live
Alarm
relay
Neutral
For range link
seecommissioning
instructions
Range
link
Test
Control
relay
Neutral
Open
Close
Note:
No Feedback
potentiometer
is required
Note:
Otheractuators
may have different
connections
Capacitance
probe
IN1
IN2
IN3
Connections to
EL5600 Series
actuators
For link position
and sensitivity see
Preamplifier IM
2
3
4
5
6
78
9
1
10
11
12
2
4
1
2
3
1
4-20 mA
current
loop 4-20 mA
input
Set point output
+
-
1
2
3
4
5
6
7
+
8
9
10
11
12 13
17
18
19
+
14
15
16
LC2200 Level controller
LC2400
Steam meter
Level
probe
Steam
Motorised valve KE/EL
Fig. 3 Three element level control
with electric valve
Make-upwater
Water
meter
+
-
4-20 mA
current
loop
Water meter
Feedback input
0-8v 0utput
Live
Neutral
X5

IM-P402-84 AB Issue 6 7
Note on 4-20 mA loops:
Steam and water meter inputs (terminals
3and 10) are earthed via the level probe.
Ensure any equipment connected to the
loop will operate with these terminals
grounded (earthed). LC2400
Water
meter
Steam meter
Level controller LC2000
Live
Neutral
Range
link
Test
Neutral
Capacitance
probe
IN1
IN2
IN1
2
3
4
5
6
7
8
9
1
10
11
12
2
3
1
4-20 mA
current
loop +
-
1
2
3
4
5
6
7
8
9
10
11
12
4
5
6
+
1
3
LC2300 Level
controller LC2400
Steam meter
Level
probe Steam
Fig. 4 Three element level control
with pneumatic valve
Feedwater
LC2300 flow controller
Pneumatic
valve
For range link
seecommissioning
instructions
Live
Neutral
Test
4-20mA
0-20mA
output -
+
Live
IN2
+
+
4-20mA
0-20mA
input -
8
10
9
11
12
7
+
+
-
-
4-20 mA
current
input
4-20 mA
current
input
Electropneumatic
positioneronvalve
Water meter
LC2300 used as
a flow controller
Test
Live
Neutral
Controller
LC2300
2
Set point output
0-20mA
4-20mA
input

IM-P402-84 AB Issue 68
6. Commissioning
The LC2400 has two channels; 'steam' and 'water', each channel consisting of a4-20 mA input
and a scaled output signal. To aid commissioning, each channel has a test input, which allows
measurementofthe4-20mAsignalwithoutbreakingtheloop.Seefigure5.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).
- Adjustthe LC2200(or LC2300)set pointpotentiometeruntilthe>50%greenLEDjustlights.
- 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 /programthesteamflowmetertooutputa4-20mAsignalrepresenting75%ofmaximum
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 /programthesteamflowmetertooutputasignalrepresenting0%ofsteamflow (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.

IM-P402-84 AB Issue 6 9
Feedwater input (Three element control using LC2200)
- Calculate the output current of the water meter when the water flow is equal to the
rated steam flow:-
Output current (milli-amps) = (rated boiler output x 16) + 4
(flowmeter range)
Note: It is essential that the units for the water flowmeter and the boiler rating are the same.
i.e that both are in kg/h or Ib/h
Example: A boiler has a rated output of 8 000 kg/h. The water flowmeter outputs 20 mA for
a maximum flow of 12 000 kg/h:-
The output current of the meter for this size of boiler is:-
Output current = 8 000 kg/h x 16 + 4 = 14.67 mA
12 000 g/h
- Calculate the water calibration value with the following formula:
Water calibration value (WCV) = 75
Output current (above mA)
i.e. For the example shown above, the output current is 14.67 mA giving a water calibration value of:
WCV = 75
14.67 mA = 5.1
Set the 'water' potentiometer to the water calibration value.
A
Steam meter
Water meter
+
-
4-20 mA
current
loop
4-20 mA
current
loop
+
-
A
1
2
3
4
12
5
6
7
8
9
10
11
LC2400
Test
Test
4-20 mA
Input
Range
link
Set point
output
0-8 V
output
4-20 mA
Input
Fig. 5
Steam channel
Waterchannel

IM-P402-84 AB Issue 610
1
23456789
110
2345678 9
10
100
100
120
60
80
40
20
140
Rise in water level Rise in water level
Steam calibration settings (SCS)
Steam calibration settings (SCS)
250
300
150
200
350
50
400
00
00
Fig. 7
Risein waterlevel less than 80 mm.PA20 preamplifier set to high sensitivity (range link fitted)
Riseinwaterlevellessthan140mm.PA20preamplifierset tomediumsensitivity(rangelinkfitted)
Preamplifier (PA20). Medium sensitivity
Preamplifier (PA20). High sensitivity
Fig. 6
Risein waterlevel less than 80 mm.PA20 preamplifier set to high sensitivity (range link fitted)
Riseinwaterlevellessthan140mm.PA20preamplifierset tomediumsensitivity(rangelinkfitted)
500
450 Preamplifier (PA20). Medium sensitivity
Preamplifier (PA20). High sensitivity