Multiquip MQP40IZ, MQP20IZ, MQP45GM Generator Set Sizing Calculations, Genset Sizing Procedure

Page 17

Generator Set Sizing Calculations

The generator set must be sized to supply the maximum starting (power surge) demands and the steady-state running loads of the connected equipment.

It is important to have the correct generator to meet the demands of the starting kVA (SkVA), starting kW (SkW), running kVA (RkVA) and running kW (RkW). A value for generator kW (GkW) is also obtained when nonlinear loads are included in the sizing calculation.

Once the starting and running loads have been determined, it is typical to add a margin factor of up to 25% for future expansion or to select a generator set of the next largest standard rating. A large connected load that does not run during usual power outages, such as a fire pump, can serve as part of a margin factor. For a fuel efficiency standpoint, the running load should stay within approximately 50 to 80% of the generator kW rating. To avoid "wet stacking", the running load should not be less than 30% of the generator set rating.

It may be necessary to oversize a generator set in applications where the voltage and frequency dip performance specifications are more stringent than usual, particularly when large motors are started across-the-line or UPS equipment is involved. Applications that involve any of the following nonlinear loads may also make it necessary to oversize the generator set or the generator:

„Static Uninterrupted Power Supplies (UPS)

„Battery Charging Rectifiers (Telecommunications)

„Variable Frequency Drives (VFD)

„Medical Diagnostic Imaging Equipment

GENSET SIZING

The use of closed-transition autotransformer starters for reduced voltage starting of large motor loads will reduce the size of the generator set required relative to across-the-line starting. Resistor-type reduced-voltage motor starting may actually increase the size of the generator set required due to high starting power factors. Wound rotor motors are the easiest type of motor for a generator set to start.

The first step is to create a reasonably accurate schedule of connected loads as early in the preliminary design as possible. A sample load schedule sheet can be found below on Table 1.

Genset Sizing Procedure

When calculating the generator size needed for the application, consider the following procedure:

Step 1. Prepare a load schedule

Step 2. Enter loads in step sequence on the worksheet

Step 3. Enter individual load characteristics on the worksheet

Step 4. Find the load step totals

Step 5. Select a generator set

Step 1. Prepare a Load Schedule

All the loads that will be connected to the generator set should be recorded on the load schedule. Identify each load as to type, power rating, and quantity. See Table 1 below for the loads listed (in italics) for an example calculation.

 

 

Table 1. Load Schedule

 

 

Load#

Load Description

Type of Load

Power Rating

Load QTY.

 

 

Examples:

 

 

 

 

Lighting

.kW

 

 

 

Static UPS

.kVA

 

 

 

Variable Speed Drives

.HP

 

 

 

Telecom DC Rectifers

.kVA

 

 

 

Motors

.HP

 

1

Water Pumps #1 & #2

Motor, Nema Code letter G,

100 HP

2

 

 

former starter (80% Tap)

 

 

2

Water Pumps #3

Motor, Nema Code letter G,

100 HP

1

 

 

former starter (80% Tap)

 

 

3

Fluorscent Lighting

Lighting

10 HP

1

INDUSTRIAL GENERATOR SETS — APPLICATION & INSTALLATION MANUAL — REV. #4 (09/07/07) — PAGE 17

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Contents Application & Installation Manual MQ PowerPage Heres HOW to GET Help Table of Contents Page Foryour Safety and the Safety of Others Safety Message Alert SymbolsAccidental Starting Safety Message Alert SymbolsGeneral Safety Important Safety InstructionsGeneral Safety Radiator Important Safety InstructionsMaintenance Safety Operation SafetyEmergencies Always know the location of the nearest fire extinguisherBattery Safety Genset should be inspected regularly for fire hazards Fire ProtectionAlways drain fuel prior to lifting Lifting the Generator SetIntroduction Always remember Safety FIRST!!! Safety involves twoIntroduction About This ManualInstallation Application and InstallationOverview ApplicationCold Climates and Derating Factors Installation OverviewLocation Outdoor LocationsGenset Sizing Procedure „ Static Uninterrupted Power Supplies UPSGenset Sizing Generator Set Sizing CalculationsStep Sequence Guidelines 765.7 Repeat steps a and b as necessary through all the worksheets Running load should not be Generator Set Sizing Calculations Select a Generator SetEstablish the minimum size required Single-Phase Induction Motor Genset Sizing Determining Load CharacteristicsDetermining Load Characteristics Lighting Calculate SkVA as follows Genset Sizing Determining Load CharacteristicsThree-Phase Induction Motors Calculate SkW as follows Determining Load CharacteristicsFull SkVA 100201 Three Phase Nema Motor Code TableVariable Frequency Drives Synchronous MotorsStatic UPS Equation above Output kVA is the nameplate kVA capacityRadiator discharge air high frequency sound Noise ConsiderationNoise Laws and Regulations Noise Zones Peak DayEnvironmental Considerations dBA Comparison Chart dBABelow estimates the noise level from multiple noise sources Adding Additional Sound SourcesDistance Effects on dBA Effects of DistanceFollowing will help reduce structure-borne noise Reducing NoiseSee on page 32 for typical measures in reducing noise Following will help reduce airborne noiseReducing Noise Acoustic MaterialMounting Access to SetMounting on a Slab Floor Mounting on a Sub-Base Fuel TankMounting Foundation Mounting FoundationVibration Isolators Mountingthe Generator SETGeneral Information Mounting Vibration Isolators Installation and Adjustment ProcedureFuel System Installation Mechanical Installation Fuel System DieselDiesel Fuel Supply TankMechanical Installation Fuel System Diesel Minimum Fuel Supply / Return Hose and Pipe Sizes Diesel Fuel SupplyMechanical Installation Fuel System Gaseous Fuels Gaseous Fuel Supply Mechanical Installation Fuel System Gaseous FuelsContaminants Natural GAS Schedule 40 Iron Pipe Sizing Pipe and Tube SizingTypical Pipe Schematic for Propane Vapor Distribution Liquid Propane Schedule 40 Iron Pipe Sizing Mechanical Installation Fuel SystemAdditional references include Fuel Storage RegulationsEnvironmental Protection Field Installing a Generator Exhaust System Mechanical Installation Exhaust SystemExhaust System Installation Mechanical Installation Exhaust System Condensation Trap Factory Recommended Engine Exhaust Silencers Exhaust System Installation Reference DataPurpose of the Battery Mechanical Installation Battery SystemMQ Power Batteries How BatteriesWorkEngine Starting System Mechanical Installation Battery System„ See the Battery Safety Instructions on New Battery Installation Mechanical Installation NEW BatteryPreparation of Charged and Wet Batteries Preparation of Dry Charged Charged and Moist BatteriesRemoving Old Battery Mechanical Installation NEW BatteryDry Charged Batteries Charged and Moist Batteries ActivationBatteryTesting Battery System -TESTING BatteryStep One 1 -Visual Inspection See Flow Chart, on next Step Three 3 Load ProcedureBattery Testing Chart Battery System Batterytesting ChartCharging LowWater-loss Batteries Battery System Charging BatteryBattery Storage Battery System Battery Charger FC & FCA Battery Charger Battery System Battery ChargerLC1224-500-2 Battery Charger FC1224-10-2011U Battery ChargerBattery Charger Safety Battery System Battery Charger SafetyBattery Charger Installation Engine Cooling Mechanical Installation -VENTILATION and CoolingVentilation and Cooling Vents and DuctsLouvers Mechanical Installation -VENTILATION and CoolingFactory Mounted RadiatorVentilation Mechanical Installation Mounted Radiator CoolingRadiator Set Requirements Mechanical Installation Mounted Radiator CoolingMounted Radiator Cooling System Remote Radiator Cooling optional Mechanical Installation Remote Radiator CoolingRemote Radiator Cooling Mechanical Installation Remote Radiator CoolingHot Well Installation Mechanical Installation Hotwell Cooling19,200/60x8 = 40 gpm Mechanical Installation Heat Exchanger CoolingHeat Exchanger Coolant Heaters Coolant TreatmentCoolantTreatment Electrical Installation DC Controlwiring Control Box DC Control Wiring Control BOX Back PanelControl box contains the following „ Digital Control Module „ Control Box Back Panel ComponentsL3 3 PH DC Controlwiring Control BOX Back PanelGenerator Set Wire Diagram AC Electrical Connections Transfer SwitchConnection Of Generator Leads For Correct Voltage Output AC Electrical ConnectionsMounted fuel tank is used, the electrical stub-up Electrical TerminationsBreaker Line circuit breakerAC Electrical Connections System Grounding Pole ATS AC Electrical Connections System GroundingEquipment Grounding AC Electrical Connections Equipment GroundingElectrical Distribution System Electrical Distribution SystemPRE-START Preparation Run the Generator Set PRE-START PreparationAppendix Installation Checklist Appendix MAIN-LINE Circuit Breaker For MQ Power Industrial GeneratorsAppendix MAIN-LINE Circuit Breaker MQ Power Industrial Generator Specifications Appendix Generator SpecificationsAppendix Generator Specifications MQ Power Industrial Generator Specifications Appendix Engine Specifications MQP175IV MQP200IV MQP250IV Appendix Engine SpecificationsGenerator Model MQP300IV MQP350IV MQP400IV Generator Model MQP30GM MQP45GM MQP60GM MQP80GM MQP100GM Appendix Engine SpecificationsMQ Power Generator Dimensions & Weights Appendix Dimensions and WeightsMQ Power Generator Dimensions & Weights Appendix Dimensions AndweightsHeres HOW to GET Help