Holiday Test – Overview; A holiday test here refers to defects in coating or lining, which are Pinhole, Void, Crack, Thin Spot or Contaminant. Holiday Test is a method for checking these defects by providing electricity through the defects in Coating/lining to Workpiece. If any area has a defect, spark or short circuit will occur. Holiday Test will be divided into two(2) main methods. According to the thickness of Coating/lining by Low Voltage or “Wet Sponge” It applies to Coat thickness less than 500 microns of High Voltage or “Spark” is used to Coating thickness greater than 500 microns. Example of understanding the methods: … Continue reading What is Holiday Test ?
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Intrinsic safety – I.S is a protection technique for the safe operation of electrical and electronic equipment/system in Hazardous Areas where any ignition source needs to be eliminated. Electrical cables are essentially sealed from damage, external electrical or magnetic fields (EMI), and isolated from non-intrinsically safe circuits. (Avoid the increase of amperes mA in I.S system –> A –> Hot spot –> Ignition -> Explosion ) I.S cables are usually colored blue so as to identify the potential risk of the electric circuit and the need for special consideration. The I.S cable to be separated from Non-I.S circuits. Hazardous areas is the … Continue reading Intrinsically Safe Cable
Continuing on MARINE COROSSION AND PROTECTION (Part 1) that we discussed about the Electro-chemical corrosion protection methods and the last remained one is called ICCP system. Reversing the current by creating an opposite potential ( ICCP : Impressed current corrosion protection ) The ICCP system, a large positive current is applied to hull and pass through the adjacent water. As a result, current flow into ship’s steel whereas it has a direct unprotected contact with seawater and inducing a Cathodic reaction that protect the steel against the corrosion. To achieve this, the Rectifier (convert AC–>DC) is connected to ship’s steel with … Continue reading MARINE COROSSION AND PROTECTION (Part 2)
To understand how marine corrosion protection works, it’s necessary to look in more detail in to the corrosion process. In this undesired chemical effect, the material can reach with different chemicals in its surroundings. The reaction can be divided into: Chemical reaction Electro-chemical reaction These reaction take place exclusively at the surface of material. It’s possible the microscopic pits are formed by corrosion on the metal’s surface.The corrosion can also occur in existing crack. CHEMICAL REACTION In chemical reaction, there’s a charge transfer between the reactions. If the exchange of charge is local effect, then the resulting ” Chemical corrosion … Continue reading MARINE COROSSION AND PROTECTION (Part 1)
Megger test is the test that evaluate the insulation resistance quality. Insulation starts to age as soon as it’s made. As it ages, its insulating performance deteriorates. Any harsh installation environments, especially those with temperature extremes and/or chemical contamination, accelerates this process. This deterioration can result in dangerous conditions in power reliability and personnel safety. As such, it’s important to identify this deterioration quickly so that corrective steps can be taken. One of the simplest tests and its required test instrument are not universally understood. To help eliminate this lack of understanding, let’s discuss in detail Insulation Resistance (IR) testing … Continue reading MEGGER/RESISTANCE TEST
There’re three general faults in electric integrity, one by one to go through and we will understand the basic concept of electric installation. Open circuit Fault Due to the broken of conductor (Wire broken) Open circuit will cause the 3-phase Motor stop (Over load relay will trip the motor if the current is over the normal ). Some case the load will be increase on the remain 2-phase and burn out the motor. Protection: Do the Megger check between one point to the earth ( The wire earthed at one end already ). The result is infinity mean … Continue reading Circuit Fault and Electric integrity protection.