Lightning: Oil&gas and petroleum industry characterized by traits such as flammability and explosive. So that the safety of electric and lightning protection are necessary for them .
Reason :
1 metal equipment and instruments including react power, frame , tank , instrument , pipeline, good conductor and cable are good conductor .
2 Flammable and explosive semi-product and product placed in Production equipment on condition of high temperature and high pressure .
3 Electronic equipment as DCS , UPS , PLC etc widely used in process of production, in that , integrated circuit is easily attacked by lightning. And it can’t afford the electrostatic voltage, specially for big scale modular equipment during the lightning strike .
Arc fault : arc , electric spark , electricity leak,short circuit, over-voltage and accumulation static are dangerous for flammable and explosive product .
Harmonic and three phase unbalance : the process of production in this industry with intensive long line , complex connection and high automation, has a large number of nonlinear equipment and power converter equipment , phase control speed and voltage regulator , high-capacity power thyristor controllable switching equipment etc . all of them causes harmonic and three phase unbalance.
1 electronic ballast : function on increasing efficiency of lamp with high frequent current .
2 Switch mode power supply : gain the pulse current from power supply.
3 UPS : consisted of rectifying circuit , converting circuit , control circuit , charging circuit , battery group, and bypass system.specifically the part of thyristor , which easily causes harmonic .
4 Converter : the side of input at rectifying circuit , the side of output at converting circuit. Both of two cause harmonic .
Effect :
1 supply and distribution of power : the loss of network influences the reliability of electronic relay malfunction .
2 Increasing the loss of transformer power, lead to overheat and disruption insulation.
3 Harmonic heightens the voltage on side of grid with capacitor and decreases the lifetime of capacitor lead to puncture it .
4 Increasing the additional load loss of transmission circuit ,lead to decrease the current of cable .
5 the parallel connection between capacitor and capacitive resistance causes the resonance at certain frequency .
6 Augment the loss leads to influence motor power and overheat motor . the resonance occurs when the frequency of harmonic closed to the rated frequency of motor.