Assignment

You are the Lead Controls Engineer for Gniewkowski Engineering Company (GEC), and our company has been awarded a contract to bid on the Installation of a Programmable Automations Control (PAC) system for the Ford Motor Company, Flat Rock Assembly Plant (FRAP), Fire Pump House (FPH) Project. The present control system in the FPH consists of various electrical and mechanical systems that are separately controlled as individual units. Ford wants us to consolidate these systems/units into I system that a PAC can control. Your job is to design a BASIC Ladder-logic program that will serve as a starting design for a future project. This job consists of the following: controlling the North Holding Tank (North Tank) and the South Holding Tank (South Tank) systems.

Attached on the following pages are EXACT PHOTOS OF THE SYSTEMS/UNITS that you can and should use as a visual aid in your Ladder-logic program. Each picture has a basic description of what it is, and there may be some additional information included that will help you with your design. Abbreviations for the systems/units are provided to assist you with your Ladder-logic nomenclature.

Attached is a Sequence of Operations that gives you a basic idea of how the systems/units operate, and how they are interconnected. There is also an attached Instruction Sheet detailing the EXACT CONDITIONS you are to implement in your Ladder-logic program. Remember, this is a BASIC design that shows how you can connect the systems/units in a PAC program; the success of your design will aid GEC in obtaining future work with Ford Motor Company.

Attached are 2 sheets of College-ruled paper that you are to use in designing your Ladder-logic program. Use the 'lines' on the sheet as a guide for EACH RUNG of Ladder-logic that you design; this makes for a concise reference for a later stage, when you will take your WRITTEN program and make a PAC-BASED program out of it, in either the Siemens or A-B program. More on that topic after this Midterm Exam.

Finally, this Midterm Exam is based upon a REAL-WORLD scenario, and should serve as a good test of your ability to utilize all the knowledge and experience you have gained so far in class. You have enough knowledge-to-date that I believe you can do this in the 90 minutes allotted.

Fire Pump House/Sequence or Operations

1. Water comes into the Fire Pump House (FPH) from (1) 12" Main Fill Line from the Flat Rock Water Supply (FRWS). This water is the Main Supply for the whole Flat Rock Assembly Plant (FRAP) facility.

2. The Fire Pump House/Control Panel (FPH/CP) senses the incoming Water Pressure and Water Flow on the Main Fill Line, and uses this input within its own internal PLC program. The FPH/CP turns on (3) Domestic Water Pumps to supply water to the whole FRAP facility.

3. The FPH/CP Domestic Water Pumps (3) can only be turned on IF Water Pressure AND Water Flow is detected from FRWS, and this information needs to be included in your Ladder-logic program.

4. The FRWS also supplies a 12" Main Fill Line for the Fire Control System (FCS) in the FPH. The FCS Main Fill Line is fed off of the FRWS incoming main line, and it is integral to the overall operation of the Fire Pump House.

5. The Fire Control System (FCS) is a separate stand-alone system that works in conjunction with the FPH/CP, but does NOT depend upon the FPH/CP being On or Off.

6. Since there is the same 12" Main Fill Line for the FCS, this means that there is (I) Main Fill Line that serves as the SOLE WATER SOURCE for the Main Fill Line that goes to both the North Tank (NT) and South Tank (ST).

7. The 12" Main Fill Line for the FCS comes into a 12" pipe 'T' that then splits to the left and right. This pipe 'T' feeds (2) valves that are electrically controlled from a Fire Water Alarm Panel (FWAP) for the North Tank and South Tank, respectively. Adjacent to the electrically controlled valves are Manual Valves (not shown) that can close off the 12" Incoming Supply Line to either the North Tank or South Tank.

8. The 12" Incoming Supply Line to each Tank is 10' above the Main Floor.

9. There is a 12" Equalization Line, 12' above the Main Floor that connects both the North Tank and South Tank to keep the water levels equal between these 2 Tanks.

10. Both the North Tank and South Tank have a Temperature Probe, located at 6' above the Main Floor that supplies the Internal Tank Water Temperature (1TWT) to a Fire Water Alarm Panel (FWAP) adjacent to the Temperature Probe. Each Tank has its own FWAP.

11. There is a 12" Outflow Line coming from the side of each Tank at 4' above the Main Floor, that feeds water to (3) separate FCS Panels and Generator Pumps in the FPH.

12. There is a Hot Water Boiler in the FPH that draws its water supply from the 12" Main Fill Line provided by FRWS. This boiler feeds Hot Water to (2) Heat Exchangers (one per Tank) that circulate Tank water through the Heat Exchanger to keep the Tanks from freezing in the winter (maintained between 50-70 degrees F).

13. There are (2) Circulation Pumps for each Heat Exchanger that circulate the Tank water through the Heat Exchanger for each Tank.

14. There are (3) separate FCS Panels and Generator Pumps that supply water to the Fire Control System for all buildings throughout the entire FRAP facility. Any activation of a Fire Condition throughout the plant will turn on 1, 2, or all 3 FCS Panels and Generator Pumps based upon demand at that time. The FCS Panels and Generator Pumps are independent of the PFH/CP.

15. ADDITONAL RELEVANT INFORMATION:

A. North and South Tank height: 31 feet
B. North and South Tank capacity/each tank: 500,000 gallons
C. North and South Tank Overflow Line to Outside: 28 feet
D. North and South Tank High Water Valve Shut-off Sensor: 26 feet
E. North and South Tank High Water Full Level Sensor: 24 feet
F. North and South Tank Low Level Alarm Sensor: 22 feet
G. North and South Tank Equalization Line: 12 feet
H. North and South Tank Incoming Supply Line: 10 feet
I. North and South Tank Temperature Probe height: 6 feet
J. North and South Tank Circulation Pump Supply/Return Lines: 4 feet
K. North and South Tank Outflow Line to Generator Pumps: 4 feet.