Note:

*1: Hazardous atmosphere is defined that atmospheric oxygen concentration below 19.5 percent or above 23.5 percent by part 1910.146 Permit-required confined spaces of the Occupational Safety and Health Administration (OSHA) standard of the U.S. Department of Labor.

shown in Table 380-1. (Source: Appendix 3 Oxygen Deficiency Hazards of Cryogenic Safety Manual by Physics Division of Argonne National Laboratory which is one of the U.S. Department of Energy's largest national laboratories for scientific and engineering research.)

Table 380-1 Effect thresholds for exposure to reduced oxygen

Article 381.

(Nothing)

Chapter 15 Energy Oil

Article 382. Oil management

1.There are three (3) main types of oil which is essential to be managed for the operation and provision including insulation oil (the oil of transformer), lubrication oil (to be used to lubricate the turbine system and diesel engine) and turbine control oil/hydraulic oil in which the first 2 types are majors.

2.Technical specifications of operation and spare oil must be conformed to the brand which is authorized by the manufacturer of facility.

3.The amount of reserve of oil must be decided in consideration of the brand, amount, distribution, price, delivery time and the like at the planning stage. Moreover, the consumption must be monitored periodically according to the administration manual.

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4.The monitoring the pressure, temperature, level, leakage and oil-line switching, and sampling must be performed according the manufacture’s O&M Manual appropriately.

5.The nature, cleanliness and degree of degradation of oil must be monitored periodically according to the related standard or Article383, 384, 385 of guideline Vol.4 or Article31-3-10, Article 31-3- 11, Article38-2-6, Article38-2-7 of guideline Vol.2.

6.The waste oil must be packed in drums and turn to oil processing plant appropriately. It is desirable to recycle it as long as the properties permitted.

7.The oil-contaminated water or used oil absorbent materials must be treated appropriately so as not to cause environmental pollution.

Article 383. Inspection of insulating oil

1. Inspection of insulating oil

Inspection of insulating oil should be performed in accordance with Articlesin Part 2 “Transmission

&Distribution Line and Substations” of the volume five of the technical guideline.

2.Polychlorinated biphenyls (PCBs)

PCBs are one of the persistent organic pollutants(POPs) which cause significant threats to human health and the environment, and are considered to be probable human carcinogens.heT Stockholm Convention on Persistent Organic Pollutants was held in 2001 to reduce and eliminate12 particularly toxic POPs eventually and some objectives for PCBs are as follows:

-To take action with regard to the elimination of the use of PCBs in equipment by 2025

-To make determined efforts designed to lead to environmentally sound waste management of equipment contaminated with PCBs as soon as possible but no later than 2028

Thus, the technical regulation bans the use ofhe telectrical equipment with insulating oil which contains PCBs unless otherwise provided the exception of the use of PCBs in a period of transition by ministry of environment. The details of the exception of the use of PCBs should be referred to related documents by ministry of environment.

Article 384. Insulating oil treatment

Since insulating oil usually provides functions of insulation and removal of the heat generated, it is required that insulating oil is refined and free from impurities such as acid, alkali and water.

1. Deterioration of insulating oil

Air movement occurs between atmosphere and electrical equipment with insulating oil by temperature varying when operation and the insulating oil may be gradually contaminated with oxygen and moisture from the air.If there is poor sealing or oil leakage by deterioration of breathers or packing,

or looseness of sealing, contamination with oxygen and moisture will be accelerated.

Since oxygen inhibitors in the insulating oil depletes withthe passage of time, the oxygen rate in the insulating oil gradually increases, and moreover, oxidation of the insulating oil which contains oxygen and moisture is accelerated by generated heat during operation.

As a result, neutralization or acid number of the insulating oil increases, and sludge will form, and the function of the insulating oil will be deteriorated eventually.

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C2H4, C3H6, CO, (CO2) because the transformer insulating oilor its solid insulation isdecomposed thermally.

Therefore, these concentrations are recommended to be analyzed gasby chromatograph not only periodically but also after electrical failure.

2. Tests to determine the acid content of insulating oil

An insulating oil sample of already known quantity is titrated with the base potassium hydroxide (KOH) until the acid in the insulating oil has been neutralized. Total acid number is represented as the amount of KOH in milligrams required toneutralize one gram of the insulating oil.A high total acid number shows high acid content in the insulating oil.

The following standards are test methods. An example of classification ofinsulating oil is shown in Table 384-1. Also, it is important to check the upward trend of this number.

-ASTM D974 - 11 Standard Test Method for Acid and Base Number by Color-Indicator Titration

-JIS C 2101:1996 Testing methods of electrical insulating oils

Table 384-1 An example of classification of insulating oil

It is recommended for determination of the overall insulating oil condition to use results of other tests such as the following together taking the manufacturer’s instructions into consideration.

-ASTM D877 - 02(2007) Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes

-ASTM D924 - 08 Standard Test Method for Dissipation Factor (orowerP Factor) and Relative Permittivity (Dielectric Constant) of Electrical Insulating Liquids

-ASTM D971 - 12 Standard Test Method for Interfacial Tension of Oil Against Water by the Ring Method

-ASTM D1298 - 99(2005) Standard Test Method for Density, Relative Density (Specific Gravity), or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method

-ASTM D1500 - 07 Standard Test Method for ASTM Color of Petroleum Products (ASTM Color Scale)

-ASTM D1524 - 94(2010) Standard Test Method forVisual Examination of Used Electrical Insulating Oils of Petroleum Origin in the Field

-ASTM D1698 - 03(2008) Standard Test Method for Sediments and Soluble Sludge in ServiceAged Insulating Oils

-ASTM E203 - 08 Standard Test Method for Water Using Volumetric Karl Fischer Titration

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-JIS C 2101:1996 Testing methods of electrical insulating oils

-IEC 60296 Ed. 4.0:2012 (b) Fluids for electrotechnical applicationsUnused mineral insulating oils for transformers and switchgear

3. Tests to determine the breakdown voltage of insulating oil

The breakdown voltage measurement of insulating oilis a test to measure the electrical breakdown voltage of insulating oil sampled from a transformer. An example of classification of insulating oilis shown in Table 384-2.

Table 384-2 An example of classification of insulating oil

4. Dealing with bad insulating oil

If a result of tests indicatesbad insulating oil, there are two options which are replacement or reclamation. The reclamation is usually performed with the process which consists of heating the bad insulating oil, filtering it through absorbent, nda recirculating it in order to dissolve, purge andfilter sludge, etc. It is recommended for dealing with bad insulating oil to take the manufacturer’s instructions into consideration.

In addition, following items are recommended to be considered during replacement or reclamation.

-If new oil supplied, the performance such as flash point or dielectric strength may not be improved.

-Using same oil or specified the manufacture is recommended in order to prevent degradation of dielectric strength and cooling capability.

-In principle, replacement or reclamationshould be performed when the transformer is not in operation.

indicates that a saturation point has been reachedThus,. it is necessary that the silica gelincluding non-indicating silica gel is replaced or regeneratedwhen approximately one-third remains with the proper color. Also, it is necessary to maintain proper oil level for the breather if it is an oil type.

Note: there is other indicating silica gel that the color changes from yellow to greenmoistureas is absorbed.

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Article 385. Hydraulic system oil for turbine

EHC and MHC are main control system for steam turbine. MHC controls governor of steam turbine

by mechanical structure composed of lever, cam, link, hydraulic relay and piston etc. MHC has mechanical lag in connection with expanding scale of steam turbine and MHC mechanical structure. Thus, EHC was developed to solve this problem and is main stream of steam turbine control system recently. This system is composed of following equipments.

-Pump (EHC high pressure oil pumps and circulating pump)

-Oil tank

-Oil cooler

-Oil strainer etc.

1.Point to be checked at daily patrol and inspection

Reliable operation of turbinedepends on proper management of each equipment by daily patrol and inspection etc. Point to be checked at daily patrol and inspection of this system is shown as follows ;

(1)Pump

1)Pump outlet pressure

2)Abnormal noise, abnormal odor, vibration and leakage

3)Heating, abnormal noise and oil leakage for bearing

4)Level, change in color and leakage for lubricant oil

5)Leakage and corrosion of piping

6)Leakage and corrosion of valves

7) Corrosion and peeling for painting etc.

(2)Oil tank

1)Oil level (high or low)

2)Oil temperature (high or low)

3)Oil leakage

4)Damage and deformation

5)Peeling of painting etc.

(3)Oil cooler

1)Oil temperature

2)Oil leakage

3)Damage and corrosion etc.

(4)Oil strainer

1)Differential pressure

2)Oil leakage

3)Damage and corrosion etc.

2.Condition of hydraulic system oil

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Condition of hydraulic system oil for turbine must satisfy used oil limits specified by the manufacturer. Sample of hydraulic system oil for EHC is shown as follows;

Table 385-1 Sample aspect of hydraulic system oil

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Reference Vietnamese standard

382

383

384

Reference Japanese standard

385

386

Reference International standard

387