1252 Perspectives

DG units will be deployed for a suite of applications. Some will be designed and installed for DG service. Some will come from installed capacity, such as emergency and standby power systems. Some will use fuel, others will use renewable resources. As a general rule, those installed for commercial, industrial, and institutional facilities will have ratings less than the full load demand of the host facility. Those used for residential facilities may be rated higher than the host facility but typically will not exceed the rating of the transformer between the facility and the distribution circuit. Retail facilities may have generation capacity near the facility full load demand. However, for the range of DG units considered in this work, the most likely scenario will be the distribution circuit having an available MVA at the point of interconnect considerably higher than that of the unit.

Figure 12. 4 illustrates a typical distribution radial feeder that would originate at a substation. Several users and user classifications are fed from the same feeder. If one of these users were particularly large with respect to the feeder's capacity, a separate feeder would be run from the substation to that facility. For example, a real-life scenario may be that residences (single phase) comprise 5 kW loads, commercial users 25 to 200 kW loads, the industrials 500 to 3000 kW loads, and one large user, for example, requires a 10 MW load to be connected to the feeder. In a worst-case scenario, the large user would be located furthest from the substation. With a 10,000 kW load, the likelihood is that this user would have a few very large unit loads (generally motors). With every starting, the motor inrush current would cause a noticeable voltage drop along the distribution feeder. Proximity would dictate how much voltage drop smaller facilities would experience. For this reason, the connection to this large user would either be at the start of the feeder or on a separate feeder entirely.

Solar Stirling Engine Basics Explained

Solar Stirling Engine Basics Explained

The solar Stirling engine is progressively becoming a viable alternative to solar panels for its higher efficiency. Stirling engines might be the best way to harvest the power provided by the sun. This is an easy-to-understand explanation of how Stirling engines work, the different types, and why they are more efficient than steam engines.

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