DOE-HDBK-1016/1-93Electrical Diagrams and SchematicsELECTRICAL DIAGRAMS AND SCHEMATICSELECTRICAL DIAGRAMS AND SCHEMATICSTo read and interpret electrical diagrams and schematics, the basic symbols andconventions used in the drawing must be understood. This chapter concentrateson how electrical components are represented on diagrams and schematics. Thefunction of the individual electrical components and the theory behind theiroperation is covered in more detail in the Electrical Science Handbook.EO 1.1 IDENTIFY the symbols used on engineering electrical drawings forthe following components:a.Single-phase circuit breaker(open/closed)b.Three-phase circuit breaker(open/closed)c.Thermal overloadd."a" contacte."b" contactf.Time-delay contactsg.Relayh.Potential transformeri.Current transformerj.Single-phase transformerk.Delta-wound transformerl.Wye-wound transformerm. Electric motorn.Meterso.Junctionsp.In-line fusesq.Single switchr.Multiple-position switchs.Pushbutton switcht.Limit switchesu.Turbine-driven generatorv.Motor-generator setw. Generator (wye or delta)x.Diesel-driven generatory.BatteryEO 1.2 Given an electrical drawing of a circuit containing a transformer,DETERMINE the direction of current flow, as shown by thetransformer's symbol.EO 1.3 IDENTIFY the symbols and/or codes used on engineering electricaldrawings to depict the relationship between the following components:a.Relay and its contactsb.Switch and its contactsc.Interlocking device and its interlocked equipmentEO 1.4 STATE the condition in which all electrical devices are shown, unlessotherwise noted on the diagram or schematic.EO 1.5 Given a simple electrical schematic and initial conditions, DETERMINEthe condition of the specified component (i.e., energized/de-energized,open/closed).Rev. 0PR-03Page 1
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