Our generator systems can deliver power to the client’s plant at Low Voltage alternator voltages such as 400V, 525V, 550V, 690V; or via suitable step-up transformers at various Medium Voltages such as 3.3kV, 6.6kV, 11kV and 33kV. We will submit the most cost-effective solution based on total generated power and power distribution needs. We prefer Medium Voltage installations for our higher power ‘generator cluster’ designs with 11kV and 33kV being the most preferred power plant voltages.
In a typical Medium Voltage installation our most common proposal is based on our proven dual LV winding step-up transformer approach. By combining two generator sets per transformer, the scope of the common MV bus is halved - a significant saving both on equipment and installation. The step-up transformers offer galvanic isolation between all the alternators and between the alternators and the MV load. The further use of optical fibre control signal connectivity implies that the generator sets are truly isolated from each other, bar common earthing and the auxiliary power feed to the units. We have done numerous case studies comparing our specific topology (2x LV generator sets feeding 1x step-up transformer) against the outright use of MV alternators (for 11kV designs) and are confident that our approach is the better one, provided that the available laydown area is sufficient to allow for the added footprint of the transformers. We need to stress however that we can supply and design around 11kV alternators should this be a specific requirement.
Our preferred LV alternator voltage for voltage step-up designs is 690V. Therefore, if requested to tender for a Medium Voltage power plant, we would generally offer 690V alternators combined with voltage step-up transformers. The 690V alternators are slightly more efficient than the 400V machines, primarily because of the lower current at the same power. The lower current also reduces cable cost and requires a smaller protection/synchronising alternator circuit breaker. Another consideration is that the 690V approach reduces the maximum fault currents on the LV circuit breakers (when the step-up transformers are connected to mains in cogeneration mode). The only reason for specifying 400V alternators would be the perceived on-sell value of the machines, but if necessary, alternator voltage can easily be scaled with an auto transformer (relatively inexpensive) to any new LV voltage of choice.
Alternator and MV system earthing are tailored to site specific requirements. Wherever possible we will offer NER (Neutral Earth Resistor) earthing in order to reduce (or eliminate) serious damage to equipment if/when earth faults occur. Our NER ground referencing designs come fully equipped with fault detection equipment which will trip the required breakers and set appropriate alarms on fault conditions.
Our smaller, stand-alone generators are offered with Automatic Mains Fail controllers. These controllers are suitable for stand-alone power generation, or for emergency standby generator applications. The down side of these controllers is that they do not support synchronizing. Our bigger generator sets are offered as ‘sync-ready’ machines. These generators are equipped with programmable controllers that will allow either generator on generator synchronizing (for multiple genset clusters) or generator onto mains synchronization (single generator with cogeneration). The sync-ready machines are equipped with motorized alternator air circuit breakers which doubles up as both synchronizing and alternator protection breakers.
We offer different Medium Voltage switchgear solutions based on a client’s existing equipment and physical requirements such as power take-off via overhead power lines, etc. We have examples of overhead open air switchgear, outdoor metal cladded switchgear, and containerized metal cladded indoor switchgear. Our preferred approach is to deliver a pre-commissioned containerized solution.
Auxiliary power: Our generators require a normal 400V/4-wire connection when on standby (except for our smaller units). The auxiliary power is necessary for the engine coolant pre-heaters (3kW/3ph devices), diesel/oil pumps (if installed), battery trickle chargers, and lighting.