MUSTHAVE

SHOULD

HAVE

COULDHAVE

Module # 150

Dealing with Process Upsets

• Objectives– Will be able to recognize an Upset

– Will be able to analyze an Upset

• Review Question– Name some causes of “Process Upsets”

Ethernet TCP/IP

Fieldbus

1

Batch

Control

Software

PAM &

CPM

Services

Measurement

Devices

Scales

& Flowmeters

FBM

What is an Upset

• What do we mean by an upset?– Abnormal event that not is not likely to be repeated

– An event which is caused by external action• Operator leaning or stepping on scale• Unbalanced mixer• Sticky valve

– An event that must not affect our working parameter• Adjusting for an event will cause errors during the next feed

– Permanent change in the process that must be fixed• Ie partially blocked pipe

– Long term will show a step change of:• Ave Flow Rate• Spill etc

– Not always detected as could still be within limits!• May require further investigation

Class Exercises A

• Place weight on scale at end of feed before DrainTime Expires• Hint: weight could be a pen or eraser.

– View results

– Be sure to inspect the “Material Transfer Process” Screen

– Make a note of:

– Spill Status, are all three still green ?

– Feed Status; what did it say ?

– There should be some indication that this was an Upset.• Did you see it?

– Do a few more feeds:

– Did the Qi adjust and remove the error

– Hint: it may or may not depending whether you were outside the 100% limits or not

Class Exercises B

• Move scale enough to cause the “StableScale” light to go OFF while trying to start a feed– View results

– Did it start ? (it should not have started)

– Be sure to inspect the “Material Transfer Process” Screen

– What error messages did you get ?

• Increase “Zero Flow Threshold” significantly– Did the feed start?

– Why?

Class Exercises C

• Increase Spill and Flow Limits for a Material Path• Introduce a large spill upset (Repeat Exercise A)

– What happened

– Did the feed complete OK

– What happened to the K1 and K2 parameters?

– Results:

– As long as the upset value fell with the 50%range of the Limits the Qi will accept the result.

• Do a few more feeds without the Upset.– Was the next feed accurate ?

– Why not?

Review Questions

• Name some causes of Process Upsets