Page 94 - E24 Electrical Notebook

90 - Diesel Generator Size Selection

Ratings as per ISO8528 Part 1:

Prime Power
Variable load. Unlimited hours usage with an average load factor of 80% of the published Prime Power over each 24 hour period. A 10% overload is
available for 1 hour in every 12 hours.

Standby Power
Limited to 500 hours annual usage with an average load factor of 80% of the published Standby Power rating over each 24 hour period. Up to 300
hours of annual usage may be run continuously. No overload is permitted on Standby Power.

Generator Selection should be based on the specific application, required rating and operational conditions. Project specific generator sizing and
selections can be offered using the FG Wilson GenSelect software tool.

GenSelect provides a library of common load types, which can be arranged into a sequence of load steps to simulate a client’s load scenario. GenSelect
calculates the requirements of the load and compares the requirements against the performance of each generating set, at the specified site conditions.

Some features of GenSelect: The Installation of a selected generator application will vary depending
on the cooling airflow requirement, the noise requirement, exhaust
• Parallel generating sets termination and fuel autonomy, etc.
• Single phase generating sets
• Additional single-phase loads (motors, UPS, battery charger, etc) To assist with designing for installation at a specific project, FG Wilson
• New load type added for modelling lifts has generated the Blueprint software tool, offering the following facilities:
• Partly loaded motors & UPS duty point
• Percent of intermittent motors • Room Planning Incorporating the following values for
• Choice of sizing algorithm • Flue Sizing & Selection k-factor based on CIBSE Guide C
• Sizing report PDF for attaching to an email • Airflow Calculation
• Selection & starting analysis dialogs (identifies which load steps have • Pressure Drop Calculator Object Shape k-factor
• Noise at Distance Calculator 1.25
determined the generating set selection) 90º Squared
Bend
Special attention should be given to generators sized to support critical
and life safety loads, such as Sprinkler Pumps and Fire Pumps, Noise at distance calculation 90º Bend 0.35 - 0.72
operating under generator supply. based on ISO3744 with turning veins (Manufacturer Specific)

90º Swept 0.67
Bend

Such critical loads may require allowance for support of the motor load SWL = SPL + 10lg (S/S0) dB 45º Squared 0.6
in Locked Rotor condition, where the stalled motor shall draw Bend
considerably more than the running/starting current, and may require to β - d2
be maintained during the starting of a standby load/motor. Consideration Sudden d1
should be given to the redundancy of supply and the overall fire strategy. Expansion
Ke = (1-β2)2
Bells Controls Equipment Ltd and FG Wilson Engineering Ltd can provide Sudden β4
assistance with such generator selections and sizings. Contraction
Kc = √0.5 (1-β2) Sin 0/2

β4

Bells Control Equipment Ltd Bells Power Ltd (Aftersales)

228 Shoreditch High Street Unit 8 Belvedere Business Park

London E1 6PJ Crabtree Manorway

Tel : 020 3259 0100 South Belvedere DA17 6AH

Fax : 020 7247 7331 Tel : 020 3259 0100

www.bellspower.co.uk sales@mcmbells.com Fax : 020 8310 0977