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>Google stuxnet plc virus Not a true virus. Someone rewrote standard Siemens PLC function blocks so that they would perform damaging actions, i.e. rapidly cycling speed control output, while showing output and speed to be normal. To get hacked function blocks into a PLC program, they...

If you wire a 24 VDC power supply in series with a loop powered flow meter, it will work. I would also wire a 250 ohm range resistor in series just to limit the short circuit current.

The advantages of H2 cooling; "Hydrogen has many advantages over air including high heat capacity and very low viscosity. Hydrogen cooled generators also have less windage/friction loss than air-cooled generators. Windage, which is caused by friction between the hydrogen and the rotor, can...

You should decide on a PID execute time between 200 ms. and 1 sec. and stick to it. PID scan time is chosen based on process time delays. More importantly is your integral time, with a deadtime of > 2 min, it should be 2 min or 0.5 repeats/min or 0.0056/sec or possibly slower. In our DCS we...

I would suggest either a multi-variable vortex flowmeter or a coriolis flowmeter as the type of flowmeter that can provide flow and density of the fluid. The coriolis meter will be much more expensive. They will transmit the density as a Hart or FieldBus variable. Both flowmeters have the...

From this link; http://www.ehawke.com/technical/wiring-systems-nec.html Cable Seals, Class 1, Division 1 Cables must be sealed at the termination. The sealing fitting, e.g. a barrier type cable gland, must provide a seal against the passage of gas or vapours through the fitting. Type MC...

Do you have minimum flow control loops and control valves on each pump? What are these control loops doing when load is reduced?

The hubs allow the cables to be sealed to prevent gas entry into the JB. A sealing compound is poured into the hub.

Look at the wide range of PLC's that Rockwell sells; from fixed IO micros, to SLC, to PLC-5, to limited size ControlLogic to multiple 13 slot chassis systems, safety PLC versions; and now the TMR SIL rated safety PLC's from ACS Triplex. And communication that ranges from DH+, DeviceNet...

> Is there any Condition where both Sov and Positioners are used in Control Valve? Yes; there can be separate interlocks or trips that open, close or lock a control valve separately from the analogue control system using solenoid valves operated by different logic. I have seen a solenoid...

All the junction box manufacturers have plastic and fiberglass boxes that are chemical resistant. Check to see what they have for replacement gaskets. If you just need a replacement gasket, check the gasket and o-ring suppliers for an acid resistant material. Check the acid resistance of...

>The problem is that I cannot upload some of the SCADA point >in Quick Builder and delete them. I am afraid that part of >points can by asynchronous with DB. Does somebody met such >kind of issue before? Uploading copies point info from server database to QuickBuilder; i.e. using up arrow...

You need to choose the server that you want to work on, and login as a individual user not an operator.

The physical distance between taps is 770 mm, and if your boiler drum always contained water at room temperature the transmitter range would be 0-770 mm WC. But you need to use the density of water at normal operating pressure and temperature to determine the actual head from 770 mm of water...

You can develop a new logic mode, setback to normal setpoint, that ramps the setpoint from 1000F to 1800F, at the rate you want. Therefore no new tuning is required. Apply logic conditions for this mode such as: -in setback mode -setpoint = 1000F -loop in auto -etc Build logic for...

You will need a SPDT switch for each level setpoint. Simply use a NO contact that closes when level is 20% to start your pump. In series with an Auto mode switch contact (auto=closed) the 20% level switch would energize the motor control start circuit and seal in the main contactor. The...

The application, the size of the pump, the flow rate, and the criticality of the system will determine if a simple level switch and motor control logic is enough or if more complex with more redundancy is required. Complete application information would improve the responses you get.

> If you know any good manuals on Triconex PLC to get a good > understanding of the system, please do send me the link. http://support.ips.invensys.com/

The turbine may overheat at the lower flow. Is there a desup station with temperature on the steam outlet? It may not operate or control well at a lower flow rate.

Your pump control can be as simple as the level switches wired into the motor control such that: 1-when in auto at 20% turn pump ON, needs a latching start circuit 2-when in auto at 80% turn pump OFF, opens to clear latch you can add timers to give a minimum pump run time. You could do...