PUMP STATION ELECTRICAL DESIGN
PUMP STATIONELECTRICAL DESIGN40 Years Lessons LearnedMaynard Wayne Robertson, PE, [email protected]@comcast.netTAUD Technology Conference Gatlinburg, TN March 13, 2013
Pump Station Design Requirements
Tennessee Dept. Environment & Conservation
Environmental Protection Agency
NFPA- 70- National Electrical Code
Tennessee Fire Marshall- Electrical Inspections
OSHA/TOSHA
TDEC RequirementsGeneral Design Requirements for Sewerage Works
Key Chapters for Pump Stations; 1, 2, 14
Chapter 2. Section 2.5 Pump Stations
Alarm System and totalizers on All stations
2.6.3 All wet well wiring to be Class l, Division l, per NEC
2.7.3 PS Capacity Greater Than - 1.0 MGDRequires Flow MetersRequires Back Up Power System
TDEC RequirementsChapter 2.6.1.6 Requires to comply with All OSHA Rules. Work place safety.
Chapter 2.7- Operability/ Reliability Do you need generator/backup power? Essentially EPA requirements.
Reliability Class 1, Class 2, Class 3.TDEC2.5 Septicity Controls. I guess something that smells BAD. Do not make it smell worse. Setting controls for minimum time in wet well.
Auto Pump Out (Timed pump start after low level contact made, low cost to reduce odor )
Electric Power Systems Chapter 1.3.11.5
www.tn.gov/envionment/wpc/publicationsDesign Criteria for Sewerage WorksNational Electrical CodeLatest Version NEC-2011
Next Version NEC-2014
Code revised on Three Year Cycle
Version adopted in Tennessee NEC-2008NFPA CHAPTER 70National Electric Code / 70E work place safety
NEC 2008 Used Statewide*Exceptions In Some Cities NEC-2011
70E Work Place General Safety Requirements
Installation Of Equipment
Protection Of Electrical EquipmentNEC-2008OrganizationChapters: One thru NineArticles Tables Appendix
Chapters: One Thru FourBasic Wiring Requirements. Apply to all Wiring Installations.
Chapters: Five thru NineSpecial Conditions
NEC ChaptersChapter 1 GeneralChapter 2 Wiring and ProtectionChapter 3- Wiring Methods and MaterialsChapter 4 Equipment for General Use
Chapter 5 Special OccupanciesChapter 6 Special EquipmentChapter 7 Special Conditions
Chapter 8 Communications Systems(Stands alone)Chapter 9 TablesAnnex A thru H ; Informational Only
Key NEC Articles for Sewer Pump StationsArticles: 200, 215, 220, 240, 250, 310, 312, Table 310.16, 400, 430, 445, 500 & 700.
Note: Entire Code Applies Always!!Tennessee State Fire MarshallRequires Electrical Inspection of all New and Modified Electrical Installations.
Require Use of Listed Equipment- UL, etc.
Current Enforcement NEC -2008
Authority Having JurisdictionEPAEPA-430-99-74-001Operability and Reliability
Class 1 Standby Power nearly always required
Class 2 Standby Power maybe Required
Class 3 Normally not RequiredService TermsService
Service Entrance
Metering
Service Disconnect
Service TypeOverheadUnderground
Single or Three PhaseAvailable fault CurrentNEC VoltageLow Voltage = Less Than 600 Volts
Single Phase120/240 VoltsMotors 5 HP or Less( 7.5 & 10.0 are manufactured)
Three Phase120/240 Volt Delta Connected120/208 Volt Wye Connected277/480 Volt Wye connected
Electrical Service EntranceCapacity for both pumps to operateService disconnect rated for service entrance and capacity to allow second motor to start without trippingService Equipment( Main Breaker and panel boards, etc.) rated for available fault currentFault Currents can be high at PS as result of large transformer and short wire runsStandard Interrupting capacity: 10,000, 22,000, 65,000ampsGrounding and BondingAdequate work space in front of electrical equipmentFor outdoor locations shield panels from sun and heatWiring Methods
NEC Article 250 Grounding and BondingTable 250.122 Size of Equipment Ground ConductorGrounded ConductorGround WireLightning protectionTable 310.16 /Table 310.15B(2)a, more than 3 conductors in raceway/conduit Conductors Rated at 75CConductors Rated for Wet Location
Control PanelsCorrect NEMA Enclosure ( 3R, 4X, etc. )Ventilation/CoolingDrainsLabeled (UL, CSA)AlarmsControl Transformer (Reduce line Noise)Instrumentation (Runtime, Volts, Amps, Calibration)Motor StartersManualAcross the Line starters( NEMA SIZE 0, 1, 2, etc.)Part windingAuto transformerSoft StartVFD (6 pulse more noise and 12 pulse less noise)VFD noise may interfere with controls/SCADA
PHASE CONVERSION
Single Phase Power to 3 Phase Power
Phase Conversion Using VFD
Size VFD Based On Single Phase Load Plus 15% 20Hp, 3P, 230V, FLA=54 Amp Based on single phase = 100 Amp Use 120 Amp VFD Common WWPS ProblemsCorrosion, Corrosion, Corrosion!!!!Electrical Junction Boxes in Wet WellsExcessive Pumps starts/ Short run timeUnlisted Electrical Equipment (Inspector Rejects)FAILURE TO DERATE CONDUCTORS in Conduit. (more than three)Lack of Phase Loss ProtectionPhase to Phase Voltage/excessive voltage difference.Poor Electrical GroundingNo Isolation of sewer gas from control Panels thru use of junction boxes with double conduit seals. Complete failure less than 1 year.Circuit Breakers too small, Result excessive heat in Panel.
Common WWPS ProblemsNO Conduit Seals, Sewer Gas direct line to control Panel.
Pump Rotation
Wrong NEMA Class Enclosures
Low Equipment Electrical withstand Ratings.
VFD noise on Control circuits
No GFIC Receptacles
Generators/ transfer switches improperly wired/ Phase Reversed.
Checklist/RecordsAlways use startup ChecklistVoltage, Line to Line, Line to Ground, Phase to PhaseAmperesDischarge HeadPumping RatePhotosNameplate DataTerminals TightWWPS Life Cycle CostInitial CostInstallationCommissioning CostMaintenance and Repairs CostENERGY COST 90 PERCENT OF TOTALHigh Efficiency MotorsHigh Efficiency Pumps
GeneratorsCorrectly Sized to start second pump with all loads energized Portable /PermanentTransfer switches/ Manual or automaticFuels/ Diesel, Natural Gas, Propane, Gasoline.Long Term maintenance cost
PUMP STATIONELECTRICAL DESIGN40 Years Lessons LearnedMaynard Wayne Robertson, PE, [email protected]@comcast.netTAUD Technology Conference Gatlinburg, TN March 13, 2013
