POWER PLANT INSTRUMENTATION & CONTROL

How to Program an 3100-series Rousemount Ultrasonic level transmitter.

June 18, 2013
First take the full range of level - say for example - 0 to 4mtr.
Now install the ULT above the level on some structural base. Clean the fase of sensor with soft tissue paper.
Now before Power up the transmitter checked that the inclination from sensor face to water is minimum...90 vertical preffred & there should not be any dust remain on sensor face. now power up the transmitter -say 24vdc, check across terminal.
before starting program see the water level is static or having riple on the surface.
now set B.erf - say 2.3 mtr (this is the distance from ensor face to water surface level) , set 4 ma = 0 , 20 ma = 20ma , & damping = 30sec in case of no ripple & 300 sec above in case of high ripple on surface of water.
After setting all this things you shall se the level in dcs as = 4mtr - 2.3mtr = 1.7 mtr (example)

after setting this check whether LE(echo lost) signal is comming on display or not , if not then your transmitter has been installed properly , if yes then please put the B.ref value properly.

incase of any doubt contact - pp.ic@rediffmail.com

Posted by Debyendu Chakraborty. Posted In : Fault Troubleshoot 

 

How to detect earthy leakage field instruments (such as limit switches) connected to Field input termination units

May 14, 2013
Troubleshooting grounding problems can be difficult at best. It was not clear what you measured your voltage in reference to. In a floating DC system, if you read a voltage to ground, you have a ground in your circuit. If you do not, then your problem lies elsewhere (a problem with your system reference?). A cross connection to a different system can be a possible cause of this problem as can a bad power supply or a wiring mistake. Also, make sure that you do not have AC in your DC...
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Posted by Debyendu Chakraborty. Posted In : Fault Troubleshoot 

 

TROUBLESHOOTING CURRENT LOOPS

April 12, 2013

Troubleshooting Current Loops


A fundamental principle in instrumentation system troubleshooting is that every instrument has at least one input and at least one output, and that the output(s) should accurately correspond to the input(s). If an instrument’s output is not properly corresponding to its input according to the instrument’s design function, there must be something wrong with that instrument. Consider the inputs and outputs of several common instruments: transmitters, controllers...


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Posted by Debyendu Chakraborty. Posted In : Fault Troubleshoot 

 

MOTOR TESTING IN FIELD

April 8, 2013
 When a motor overload or circuit breaker trips and /or blows fuses, certain procedures and tests should be carried out:

* lockout and tag out main circuit breaker;

* test insulation resistance of motor wires and windings by using megohm meter between T1, T2, & T3 leads and ground, then;

* test "T" leads to motor with ohmmeter for continuity and ohm-age of windings between A to B, B to C, A to C; each resistance should be within 1 or 2 ohms of each other; if the ohms readings are significantly d...
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Posted by Debyendu Chakraborty. Posted In : Fault Troubleshoot 

 

PROGRAMABLE LOGIC CONTROLLER

April 8, 2013
* check to ensure main power is on( 110 VAC)

* check 24V dc power available

* identify problem area

* check sensor operation in problem area

* check sensor Inputs to PLC

* check on PLC that a change in sensor state causes the corresponding Input LED on the PLC to go on or off

* identify Output controlled by Input on PLC ladder diagram

* ensure that Output LED is cycling on/off with Input

* check that Output voltage is correct and cycling on/off with Input

* locate Output device and ensure that voltage...
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Posted by Debyendu Chakraborty. Posted In : Fault Troubleshoot 

 
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