NFPA 70B-2002 Recommended Practice for Electrical Equipment Maintenance

NFPA 70B-2002 Recommended Practice for Electrical Equipment Maintenance. 3.3.13 Grounding Electrode System. The interconnection of grounding electrodes. 3.3.14 Grounding-Type Receptacle. Areceptacle with a dedi- cated terminal that is to be connected to the equipment grounding conductor. 3.3.15 Harmonics. Harmonic voltages or currents are those voltages or currents whose frequencies are integer multiples ofthe fundamental frequency. 3.3.16 Noise. Undesirable electrical signals in an electrical or electronic circuit. 3.3.16.1 Common Mode Noise. Undesirable electrical sig- nals that exist between a circuit conductor and the grounding conductor. 3.3.16.2 Transverse Mode Noise. Transverse mode noise, sometimes referred to as normal or differential mode noise, is undesirable electrical signals that exist between a pair of cir- cuit conductors. 3.3.17 Power Transformers. Determines the type of trans- former and is defined as those larger than 500 kVA, while dis- tribution transformers are those 500 kVAor smaller. 3.3.18 Protective Conductor. (See29.2.23, Equipment-Grounding Conductor.) A conductor required by some measures for protec- tion against electric shock for electrically connecting any ofthe following parts: exposed conductive parts, extraneous conduc- tive parts, ormain(grounding) earthingterminal.Alsoidentified in some instances as the protective external (PE) conductor. 3.3.19 Qualified Person. One who has the skills and knowl- edge related to the construction and operation ofthe electri- cal equipment and installations and has received safety train- ing on the hazards involved. 4.1 Why EPM? 4.1.1 Electrical equipment deterioration is normal, but equipment failure is not inevitable. As soon as new equipment is installed, a process of normal deterioration begins. Un- checked, the deterioration process can cause malfunction or an electrical failure. Deterioration can be accelerated by fac- tors such as a hostile environment, overload, or severe duty cycle. An effective EPM program identifies and recognizes these factors and provides measures for coping with them. 4.1.2 In addition to normal deterioration, there are other potential causes ofequipmentfailure thatcan be detected and corrected through EPM. Among these are load changes or additions, circuit alterations, improperly set or improperly se- lected protective devices, and changing voltage conditions. 4.1.3 Without an EPM program, management assumes a greatly increased risk ofa serious electrical failure and its con- sequences. 4.2 Value and Benefits of a Properly Administered EPM Program. 4.2.1 A well-administered EPM program will reduce acci- dents, save lives, and minimize costly breakdowns and un- planned shutdowns of production equipment. Impending troubles can be identified — and solutions applied — before they become major problems requiring more expensive, time- consuming...