Eurotherm/Barber-Colman 2704 Packaged Boiler Controller

2704 Packaged Boiler Controller

	Boiler Pressure	Water Level	Total Dissolved Solids
Process Inputs	4-20mA	4-20mA	4-20mA TDS Probe (conductivity)
Control Outputs	4-20mA Dual relays	4-20mA Dual relays	4-20mA Dual relays
Control Functions	PID Valve position	PID Valve position	PID On/off control Valve position
Alarms	High, low	High, low	High, High-High
Standard Features	Main steam warm up	Single element	Timed bottom blowdown Temp - compensation Probe diagnostics
Calibration	Factory set	Factory set	User calibration
Advanced Features	Maths & Logic blocks timers & real time clock
Communications	Modbus RTU, Modbus master, Profibus DP, Devicenet
Power Supply	82-264Vac, 24Vdc/ac

Total Dissolved Solids

Conductivity probe or 4-20mA input
Auto or manual temperature compensation
TDS purge output
Probe diagnostics
Simple user calibration
Trend view of SP and PV

The 2704BC is compatible with TDS conductivity probes or probes with internal transmitters providing 4-20mA. Shipped for connection to 2-electrodes TDS probes it can also be used with 3 or 4-electrode sensors. When used with 3 or 4 electrodes probe scaling can be detected automatically and alarmed upon.

Units can be either µS/cm@25°C or PPM and the user can select automatic or manual temperature compensation of the conductivity reading.

For boilers where the TDS probe is mounted in a blowdown line, the TDS purge feature will switch on the TDS control relay for a short time allowing water to pass the sensor, therefore ensuring that the TDS measurement is at the same temperature as the water in the boiler.

Probe diagnostics are available that will indicate to the boiler operator that the probe scaling is causing inaccuracies in the measurement and that the probe should be cleaned or replaced.

Changes in the physical properties of the probe (scaling) means that periodic calibration of the TDS is required. The 2704BC implements an extremely simple procedure where the user simply enters the value that he wants the TDS to read.

Timed Bottom Blowdown

3 Blowdowns per day
Uses real time clock
Interface to valve switch
High integrity blowdown network

Timed Bottom Blowdown is a standard feature of the 2704BC and is performed to remove the sediment that accumulates at the bottom of the boiler. It is normally carried out at least once per day.

A high integrity network connection between Boiler controllers ensures only one boiler is blowing down at any one time. This is essential because the blowdown-receiving vessel will usually only be sized to cope with one Boiler blowdown at a time.

Water Level

4-20mA or 0-10Vdc input
Simple calibration
High and low alarms
Analogue output to invertor drive
Direct interface to motorised valve

The 2704BC interfaces easily with level transmitters providing signals in the range of 4-20mA or 0-10Vdc, and implements single element level control. For 2 or 3 element control please contact your local Eurotherm representative.

Using a simple calibration procedure the user can range his electrical input signal to be proportional to the low and high water points within the boiler.

Low and high level alarms are provided for indication to the operator that a problem may exist within the boiler.

The 2704BC can cater for either a 4-20mA control output to an invertor drive or a direct relay connection to a motorised valve. Simple On/off control can also be configured if required.

Boiler Pressure

4-20mA or 0-10Vdc input
High alarm
Direct connection to motorised valve
4-20mA interface to combustion controller

The 2704BC can perform closed loop control of boiler pressure, interfacing with standard pressure transmitters providing signals in the range of 4-20mA or 0-10Vdc. The user can select between PSI and Bar units.

The control output from the controller will either be 4-20mA or relay outputs providing direct positioning control of motorised valves. Alternatively, the 4-20mA demand signal may be interfaced to a specialist combustion control system to provide stoichiometric Fuel/Air ratio control.

Main Steam Warm Up

Gradual opening of crown valve
Uses real time clock

To prevent inrush into the outlet pipe the Main Steam Warm Up feature will gradually pulse open the crown valve. The open and Close times are set by the user.

Programmer Enhancements

Asynchronous Setpoint Programmer
The 2704 now has the ability to run up to 3 independent setpoint profiles. Prior to V6.00 all profiles had to follow a common timebase and have the same number of segments. Now profiles can start and stop at different times, have different number of segments in each, and run totally independent from each other. Each profile can be stored as 20 separate programs.

A feature called 'RUN GROUPS' has been introduced to allow profiles to be stored together in groups of up to 3 therefore allowing profiles within a group to be controlled by common RUN, HOLD & RESET commands.

Advanced Editing
Features have been introduced to allow Insertion and Deletion of segments and also Copy and Paste of complete programs.

Digital Output Names
It is now possible to assign User Text to Program Digital Outputs to provide an operator with a meaningful description of the function of the output. This name will appear to the operator when editing a program.

Additional Programs for Synchronous Programmer
The maximum Synchronous Programmer program capacity has been increased from 50 to 60 programs.

Multiple Input Block
This feature allows the maximum, minimum, average or sum of up to 6 inputs to be calculated. Typically used with analogue inputs in furnace applications, it can also be used with digital inputs as a 6 input OR or AND gate, using the MAX and MIN operators respectively. This block is available when Toolkits are enabled. One block is provided in level 1 and three blocks in level 2.

Patch Wiring
The patch-wiring block provides a point to point wiring feature, providing the facility to soft wire together parameters that do not have 'Wire' associated with them. Typical examples include Alarm Setpoints.

32 Patch Wires are provided in the 2704 and are available when Toolkit 1 is enabled

Local SP ramp Servo to WSP
When SP ramp is enabled and the setpoint is altered an option has been introduced to allow the setpoint to start ramping to the value from the current working setpoint instead of from the current PV.

Analogue Operators
The number of Analogue Operators available in Toolkit level 2 has been increased to 32.

User Values
The total number of User Values has been increased to 50. 10 are now included as standard in every 2704, 30 are included in Toolkit level 1 and 50 in Toolkit level 2.

Master Communications
100 master communication parameters are now available and 16 slaves are supported.

EI-Bisync Parameters
The following additional parameters are now supported

AH	Tuning power High Limit
AL	Tuning power Low Limit
as	Tune State
C5	User Value 5
C6	User Value 6
C7	User Value 7
C8	User Value 8
CP	Run Program number
CS	Running Segment number
Pt	Running Segment type
TM	Segment Time Remaining
WD	Program Logic
ws	Loop Status

Last Updated Friday, July 29, 2005