The 30th Street Pump Station on was bid gone bad. The estimate was transferred
between two different people and items fell thru the cracks and were left out of
the bid. We bid $60,000 and the next closest bid was $120,000. We took the job
to save reputation. I was made Project Manager with the direction to try and not
loose the other half of $60,000.
I set out to find cost effective alternatives to what was in the specification
and try to get them accepted by the engineer. The original design had an Allen
Bradley PLC for control. To transfer status and commands back and forth with the
main plant the I/O was mirrored to outputs/inputs that were wired into
inputs/outputs on an RTU that was connected via lease-line modems to an RTU at
the main plant. Then its outputs/inputs were wired to inputs/outputs in an AB
RIO rack. I was able to get the engineer to accept removing the 'extra' cards
from both AB PLC's and eliminating the RTU's and simply put a Prosoft
communications module in each AB rack. I was able to save about $50,000 not just
on PLC hardware costs but in panel size, number of terminals, configuration and
testing to name a few.
We had testing the communications in-house and everything worked great, but
after the hardware installation was complete we tried to bring the
communications up and could not get it to work. After four weeks of trying and
bring in other specialists it was determined that US West was not providing us
with what we had asked for, despite their constant insistence that they had, and
we tried to get them to fix their problem. After another four weeks of working
with US West to try and solve the problem we convinced the client that a dial-up
connection that never hung-up was an easier and more cost effective solution.
After receiving new modems we had communications up and fully tested in 24
hours. This did cost us an addition $10,000 in wasted time and parts that we
were unable to recoup from US West.
Although the project lost money I feel that it was a personal success. I have
included the some panel and I/O drawings.
As part of this project I also modified and added to their existing Intellution
Fix32 HMI screens.
Drawing Package (.pdf