IEEE 1547.6:2011 pdf free download – IEEE Recommended Practice for Interconnecting Distributed Resources with Electric Power Systems Distribution Secondary Networks
3.1 Definitions
For the purposes of this document，the following terms and definitions apply. The IEEE StandardsDictionary: Glossary of Terms & Definitions should be consulted for terms not defined in this clause.”
cable limiter: See: network limiter.
contingency (contingencies): The number of coincidental distribution system equipment outages (e.g.,feeders) that can be tolerated without adversely affecting the character of customer service. Distributionsystems can be categorized with respect to the allowable contingencies accommodated while still supplyingcustomer load reliably.For instance, a radial distribution system is identified as a zero-contingency designbecause the loss of the primary feeder would result in a customer outage and thus seriously affectassociated customers. Some arca networks are designed and operated to a second-contingency criteria, andin these distribution systems, two primary feeders can be out of service without affecting customer service.
cycling: Undesirable repetitive tripping and closing of a network protector (NP) because of variations inloading and other conditions.
distribution secondary network: An ac distribution system where the secondaries of the distributiontransformers are connected to a common network for supplying electricity directly to consumers. There aretwo types of secondary networks: grid networks (also referred to as area networks or street networks) andspot networks. Syn: secondary network.
dynamically controlled inverter (DCI): An inverter with the capability to govern its power output basedon an input control signal.
grid network: A secondary network system with geographically separated network units (NUs) and thenetwork-side terminals of the network protectors (NPs) interconnected by low-voltage cables that span thedistance between sites.The low-voltage cable circuits of the grid networks are typically supplied bynumerous NUs. A grid network is also referred to as an area network or a street network.
interconnection study: A study to ascertain the effect of parallel operation of a distributed resources (DR)on the distribution network system. It may be used to determine the scope and cost of the modificationsneeded to accommodate parallel DR operations.
network limiter: An enclosed fuse for disconnecting a faulted cable from a low-voltage networkdistribution system and for protecting the unfaulted portions of that cable against serious thermal damage.Syn: cable limiter.
network master relay: A relay that functions as a protective relay by opening a network protector (NP)when power is back-fed into the supply system and as a programming relay by closing the protector inconjunction with the network phasing relay when polyphase voltage phasors are within prescribed limits.
network protector (NP): An assembly composed of a circuit breaker and its complete control equipmentfor automatically disconnecting a transformer from a secondary network in response to predeterminedelectrical conditions on the primary feeder or transformer and for connecting a transformer to a secondarynetwork through manual or automatic control responsive to predetermined electrical conditions on thefeeder and the secondary network. The NP is usually arranged to automatically connect its associatedtransformer to the network when conditions are such that the transformer,when connected,will supplypower to the network and to automatically disconnect the transformer from the network when power flowsfrom the network to the transformer.
network system: A collection of spot networks，secondary grid networks，or combinations of suchnetworks and the primary feeders that supply them.
network system reliability: A measure of the degree of certainty that the network system will perform itsrequired functions under stated conditions for a stated time. Typical indices used to measure the reliabilityof a network system include the number of service interruptions (i.e., a complete loss of voltage), thefrequency of service interruptions, and the duration of interruptions.
network transformer: A transformer designed for use in a vault,or other location, to feed a variablecapacity system of interconnected secondaries. It usually, but not always, has a provision for attaching anetwork protector (NP). It can also have provisions for primary grounding or disconnection.
network unit (NU): This unit consists of a primary disconnect andor grounding switch， a networktransformer, and a network protector (NP) with its controls, protection, and communications.