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Control.com member...
Member Information and Posts by BruceD
Topic: Engineering and workplace issues.
from the Proces Control department...
Exe certification
Originally posted by Sumesh on 1 April, 2014 - 3:13 am
Exe certification of a junction box
New Replies:
The best place to ask this question is with the supplier of the equipment, rather than a generic...
Topic: Human-Machine Interface and SCADA.
from the Automation List department...
Android tablet for HMI?
Originally posted by Ken E on 3 June, 2011 - 11:18 am
Using an Android tablet as an all in one PLC.
New Replies:
You need to connect the power supply lines in the USB connection to a high-current source that can...
Topic: Engineering and workplace issues.
from the Forum department...
How to replace my old EX d enclosures
Originally posted by Ibrahim Abdelmohsen on 6 January, 2014 - 6:01 am
When replacing old EX d enclosure, is there any problem to order new EX d enclosure and put the old components on it?
New Replies:
Sorry - but this advice is not correct. Under IEC rules, a bare Ex d enclosure will be certified...
Topic: Information resources, documentation.
from the School department...
Wet Leg Pressure Level Measurement
Originally posted by Jerry on 15 March, 2014 - 8:29 pm
Need assistance on Wet leg pressure level measurement situation
New Replies:
(There is no reason why the seal liquid should have an SG greater than the process fluid - if the...
Topic: Power generation equipment control.
from the Forum department...
Changing Careers looking for advice
Originally posted by surya on 10 February, 2014 - 6:28 am
Please give me some guidelines that i am changing my careers from mechanical stream to instrumentation
New Replies:
As long as he doesn't take the plant with him ......
Topic: PLCs and related questions.
from the Forum department...
Project ideas for getting into automation?
Originally posted by Rhonage on 15 February, 2014 - 9:59 pm
I'm learning from scratch to be an automation engineer. Where should I start?
New Replies:
The essential basic concepts for automation, process control, etc all reduce to one thing -...
Topic: Power generation equipment control.
from the Forum department...
Speed of Synchronous Generator
Originally posted by Muhammad Salman on 26 February, 2010 - 4:08 pm
Why Speed of Synchronous Generator decrease with increasing speed?
New Replies:
There is a fundamental principal in physics which is essential to grasp in control systems analysis...
Topic: Engineering and workplace issues.
from the Electrical department...
Harardous Area Verification Dossier
Originally posted by Biky on 2 February, 2014 - 11:53 pm
Trying to understand Harardous Area Verification Dossier
New Replies:
A good starting point is IEC 60079.14 section 4.2. This lists the requirements for the dossier...
Topic: Engineering and workplace issues.
from the Instrumentation and Control department...
Compensation for level measurement
Originally posted by bhargav purohit on 20 January, 2014 - 8:52 am
compensation in level measurement for temperature
New Replies:
Boiler water is saturated so the temperature and pressure are related - if the pressure is known,...
Topic: Engineering and workplace issues.
from the Instrument department...
Generic pressure transmitter in SIL determination
Originally posted by Ricardo Almarza on 14 August, 2009 - 2:59 pm
Doubts about "generic" instrument
New Replies:
When thinking about this, bare in mind the following ... - any laboratory-based safety...
Topic: Engineering and workplace issues.
from the electrical department...
d.c.machine
Originally posted by electrical on 26 December, 2013 - 7:04 am
doubt about relationship between speed and torque?
New Replies:
Torque is directly proportional to current - but speed is directly proportional to voltage. In a...
Topic: Software, including programming, OS issues, etc.
from the software department...
modbus floating point format
Originally posted by mbusland on 21 December, 2013 - 9:34 pm
Is it mandatory to use IEEE Format for representing floating point in 2 16bit registers?
New Replies:
Nothing wrong - but don't call it floating point because it isn't. What you are proposing is to...
Originally posted by Maryam on 14 December, 2013 - 9:51 am
Hi
I am searching about different ways to produce electricity by water.
New Replies:
Power available in watts is the product of pressure drop in Pa and the volumetric flow in m^3/s. 10...
Topic: Application Questions and Problems
from the Forum department...
Android touch panels
Originally posted by dex on 13 June, 2013 - 8:52 am
Best Android touch panels with IP protection
New Replies:
Samsung Tab 10.1 and Asus/Google Nexus 7 both do - I'm using them as masters to control some stuff...
Topic: Information resources, documentation.
from the Forum department...
Route to enter the industry
Originally posted by Jimmy on 5 June, 2013 - 5:06 pm
How to get in to the automation industry. What do I knowledge do I need and the best way get past HR / get to interview..
New Replies:
Debugging communications is a good example of what I meant by getting two systems to talk to each...
Topic: PLCs and related questions.
from the Forum department...
Why 250mA fuse for 4-20mA analog input?
Originally posted by Mohamad Ashour on 9 May, 2013 - 5:31 pm
Why 250mA fuse for 4-20mA analog input?
New Replies:
25V / 250 ohms = 100 mA, so a 250 mA fuse is not going to do this job - 50 mA might....
Many 4-20 mA transmitters will pull 25 mA in the event of an internal fault, or if a seriously...
Topic: Power generation equipment control.
from the Forum department...
Magnetizing Current
Originally posted by Noel Brady on 3 May, 2013 - 1:26 pm
Power factor in electrical generation systems
New Replies:
In an electric motor, the torque is developed by the interaction between the stator current and a...
Topic: Information resources, documentation.
from the Forum department...
Steam flow through valve
Originally posted by engineer on 24 April, 2013 - 10:45 am
Steam flow through a valve
New Replies:
It depends on the valve characteristic - for a typical large turbine, the curve of flow vs opening...
Originally posted by praveen on 7 April, 2013 - 3:35 pm
Temperature compensation for density variation of air in hydrostatic measurement
New Replies:
It also undergoes a fairly rapid change in temperature if the machine is filled with cold water and...
FWIW ... I recently dismantled a discarded washing machine, mainly to get at the motor for use...
Topic: Engineering and workplace issues.
from the Forum department...
Junction Boxes for zone 0
Originally posted by Ibrahim Abdelmohsen on 27 March, 2013 - 7:16 am
what is the minimum requirements for junction box in zone 0?
New Replies:
The only requirements in IEC60079.11 relating to enclosure design refer to Ingress Protection. As...
Topic: Information resources, documentation.
from the Department of Redundancy department...
Variety of jobs in automation
Originally posted by MC on 14 March, 2013 - 10:30 am
Learning about different aspects of automation and gaps in learning
New Replies:
Profibus is a very minor technique in a very large field - I am also 66+ and have never come...
Topic: Engineering and workplace issues.
from the Forum department...
Implementing PID Controller with C++
Originally posted by tvlas on 6 March, 2013 - 3:28 am
Question about how a PID Controller might be implemented in C++. How to go from continuous to discrete signal in C++?
New Replies:
First you need to take samples of the value to be controlled at finite intervals - the calculation...
Topic: Engineering and workplace issues.
from the Forum department...
Intrinsically safe barrier required?
Originally posted by Jordan on 21 February, 2013 - 6:22 pm
When are IS barriers required?
New Replies:
You always need some sort of energy limiter (barrier or isolator) between powered equipment and a...
Topic: Application Questions and Problems
from the Placing the blame. department...
Risk assessment responsibility
Originally posted by Tom Bullock on 19 February, 2013 - 10:34 am
Who is responsible for risk?
New Replies:
Only the final end-user can do a full risk assessment, taking into account things like the...
Topic: PLCs and related questions.
from the Forum department...
Error of proportional only controller
Originally posted by Asad Khan on 10 February, 2013 - 10:23 am
Error of proportional only controller
New Replies:
A mathematical model of the controller is very easy - the output is proportional to the offset. In...
The "error from the setpoint" IS the offset....
You can ESTIMATE the offset (not calculate it precisely) if you realise that the proportional band...
Topic: Power generation equipment control.
from the Forum department...
Synchronous Generator Voltage
Originally posted by Rudy on 12 February, 2013 - 11:50 am
AC generator voltage,excitation current, voltage drop and power flow
New Replies:
> But this makes me think that the VARS out of the generator could be controlled by the...
Now you've got me thinking ... You're on the right track with your mental model. Unfortunately,...
There is a phenomenon in electrical systems called reactance. This applies to AC-only systems, and...
Topic: Application Questions and Problems
from the Forum department...
Safety risk assessment
Originally posted by Tom Bullock on 5 February, 2013 - 11:20 am
Safety risk assessment report
New Replies:
This raises another point often overlooked during development of a safety system.. You need to...
I think the size of the team involved depends on the circumstances. For a new plant where a...
A very broad-brush approach would start with the following headings: . What could go wrong? -...
Topic: Human-Machine Interface and SCADA.
from the I might be wrong but I doubt it. department...
High Performance HMI
Originally posted by old guy on 7 February, 2013 - 11:45 pm
Most successful HMI design of all time.
Contradictory trend in HMI design? You tell me.
New Replies:
The problem with gratuitous moving, flickering, flashing etc is that it can interfere with the...
Topic: Sensor technologies.
from the Instrumentation department...
Wrong Thermocouple Extention Cable
Originally posted by Benjamin Pazolli on 29 January, 2013 - 12:24 am
What is the error if you use a Tx cable with a K thermocouple?
New Replies:
I can quite believe it - especially if the guy responsible for the original design is now...
Yep - there are two extremes. If the terminals in the thermocouple head are at more or less the...
The best way to make an estimate of the error is to set up a test system - stick a Type K in a bath...
Type T will have one leg of copper - which is copper-coloured ......
Topic: The Business of Automation and Control
from the To be or not to be. department...
Safety risk assessment??
Originally posted by Tom Bullock on 30 January, 2013 - 11:18 am
Should one perform a formal safety risk assessment?
New Replies:
Check out the ALARP** principle - this indicates that there is formal recognition of the need to...
Topic: Power generation equipment control.
from the Power Generation department...
Islanding of Parallel Generation
Originally posted by BairdUK on 28 January, 2013 - 9:13 am
Looking to determine AVR and generator response during islanding of site from National Grid.
New Replies:
The actual behaviour when islanded will depend on what is used as set-point and PV for the AVRs. ...
How can I resist a challenge like that! Some further information would be useful - - what is...
Originally posted by Marc on 23 January, 2013 - 2:32 pm
Can there be an issue with running Serial modbus and TCP modbus on the same computer at the same time if some of the addresses are the same?
New Replies:
As long as the receiving computer can distinguish between the target hardware items, the addresses...
Originally posted by Tim on 23 December, 2012 - 9:47 pm
Are most automation equipment broken down into finite state machine logic?
New Replies:
According to IEC61131 Table 46, there are three variants on the divergence of sequence. All three...
An SFC is made up of transitions and actions - a check for a particular result will trigger a...
I find that using an SFC approach to the design stage of a complex sequence can highlight all the...
Topic: Continuous process industries, DCS questions.
from the Instrument Control department...
About Control Valve Selection
Originally posted by papaya on 4 October, 2009 - 11:08 pm
Process of selecting Control Valves & DCS settings
New Replies:
CV is a constant relating the flow through a control valve to the pressure drop across it. The...
Originally posted by Jason Alsin on 19 December, 2012 - 3:55 pm
What is the best approach to control a VFD pump speed in order to keep both a minimum pressure and a minimum flow in the distribution loop?
New Replies:
You can quite safely operate a selective control scheme with both pressure and flow controllers. As...
Topic: Engineering and workplace issues.
from the Automation List department...
EEx ia vs EEx [ia] vs [EEx ia]
Originally posted by Rashid on 19 November, 2012 - 10:32 am
EEx ia and EEx [ia] and [EEx ia] and isolation barrier
New Replies:
The first thing is that you need to find out exactly what specific codes and standards are...
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