A generating set is four decisions that have to agree with each other: the rating, the engine, the alternator and the control system. This page is what we do about each of them before a set leaves the building.
Sizing and rating selection
We start from the load schedule and the duty class. ISO 8528 defines the rating labels, and they are not interchangeable. A standby rating (ESP) is a variable load with no overload allowance, for use when the utility supply fails. A prime rating (PRP) is a variable load for unlimited hours with a permitted overload. A continuous rating (COP) is a constant load for unlimited hours. Quoting a standby rating for a set that will actually run prime is the most expensive mistake available at this stage.
Site altitude and ambient temperature both derate the set. So does a restricted intake or a long exhaust run with high back pressure. We apply those before confirming a number rather than after commissioning.
Engine and alternator matching
The alternator is selected for the transient case, not the steady-state one. Winding pitch determines how the machine behaves with third-harmonic current in the neutral. Subtransient reactance determines how far the voltage dips when a motor starts direct on line. Excitation method determines whether the AVR still has a usable supply when the load is heavily distorted. We calculate voltage dip and recovery for the actual starting sequence and state the result on the quotation.
Control system
Standard builds use a mains-failure controller with configurable start attempts, engine protections, and volt-free contacts for a building management system. Multi-set installations get synchronising, load sharing and load-shedding priorities configured against the real distribution board schedule at commissioning. Remote monitoring runs over Modbus on the same panel.
Load-bank testing
Every set is run on a resistive load bank in steps to its full rating. We log voltage and frequency regulation at each step, coolant and exhaust temperatures, oil pressure, fuel consumption, and the response of every alarm and shutdown. A no-load run proves the set starts. A load-bank run proves it can carry what it was sold to carry, and it is the only way to find a cooling or fuel restriction before the customer does.
Commissioning support
On site we witness the transfer sequence with the transfer switch, set the start, transfer, return and cool-down delays against the actual load, and repeat a load test where a load bank is available. The commissioning record is written down and handed over, not described verbally.
[Client to confirm which commissioning services are offered in each region, and any third-party witness testing arrangements, before this page is published.]