Shin Ho Chemical co.,Ltd

Technical Data

The Function of Insulating Oil
1. Cooling Action

The heat which is produced from the inside of electric transformer is transferred to the insulating oil, and the biggest factor which makes an influence to the cooling action of insulating oil is viscosity. So low viscosity oil is used as an insulating oil since the lower viscosity is the better cooling action.

2. Insulation Action

Excellent insulation characteristic is necessarily required as an insulating oil.

Impurity Remarks Bad Influenced Insulation Characteristic
Moisture Free Moisture, Dissolving Moisture, Emulsification Moisture Breakdown Voltage, Dissipation factor ,Volume Resistivity
Fibric Material Filter paper Breakdown Voltage
Dust Dust in the air,Metal powder of fine particle Breakdown Voltage
Oxidation Production Sludge, Organic acid Breakdown Voltage, Dissipation factor ,Volume Resistivity
The Properties What Insulating Oil has to be equipped
1. Excellent electric characteristic

A. Breakdown Voltage
B. Volume Resistivity
C. Dissipation factor

2. Excellent Oxidation Stability

Excellent insulation characteristic is necessarily required as an insulating oil.

3. Excellent Cooling Performance
4. Lower Evaporation, High Flash Point
5. None of Corrosivity
6. Low Pour Point
Degradation Process & Conditions of Insulating Oil
1. Oxygen

Insulating oil has been oxidized bit by bit by the oxygen in the air or oil when it is used. Degradation is the phenomenon what makes lower performance as an insulating oil by increasing acid value and producing sludge by oxidation

Volume resistivity
(80℃) Ω㎝
Total Acid Number
Interfacial Tension
more than 1×10¹¹ 0.00~0.005 more than 40
1×10¹²~1×10¹¹ ~0.150 20~40
1×10¹¹~10¹º ~0.250 10~20
Total Acid Number (mgKOH/g) 0.20 0.25 0.30 0.35 0.40 0.50
Sludge(%) 0.005 ~
0.005 ~
0.050 ~
0.070 ~
0.090 ~

2. GAS Product

Oil Circuit Breaker, even though it is momentarily, produce GAS. It is mainly hydrogen and hydrocarbon GAS, and sometimes couldbe the reason of explosion

3. Catalysis of Metal

Various kinds of metal accelerate degradation of insulating oil.

Accelerated metals for the oxidation of insulating oil Not influenced metals to the oxidation of insulating oil
Copper, copper oxide, iron, brass, bronze, silver, chromium, manganese,
copper + lead, lead + zinc, copper + aluminum, copper + copper oxide
Tin, Aluminum, Zinc, Lead, Nickel, Cobalt, Titanium
4. Ray of Light

One of the degradation reasons is ray of light, especially ultraviolet rays action is remarkable.
According to the test what irradiates various wave length ray of lights to the insulating oil, there are no spoilage under circumstances without oxygen, but included ultraviolet rays of light accelerate degradation.

Degradation of Insulating Oil by Dissolution of Insulating Materials

1. Dissolved Case of Insulating VANISH

Dissolution of very little insulating Vanish
makes influence to the Saponification Value

2. Dissolved Case of Insulating COMPOUND

Dissolution of insulating Compound
makes stronger Fluorescence

Maintenance of Electric Insulating Oil and Replacement Time
1. Relationship between Total Acid Number and Interfacial Tension

General replacement time to the new insulating oil is that the total acid number reaches around 0.2~0.3mgKOH/g.

Sample Total Acid Number
Interfacial Tension
1 0.08 29.5 The test has been done after remove moisture, sludge and dust by filtering
2 0.15 29.8
3 0.21 19.3
4 0.22 19.2
5 0.41 14.1
6 0.44 16.4
7 0.51 15.1
8 0.54 15.5
9 0.68 13.7
10 0.78 13.5

2. Relationship between Total Acid Number and Insulating Action

The characteristic of insulating oil which total acid number is around 0.2~0.3mgKOH/g is influenced by outer circumstances, especially by dissolved moisture in the insulating oil.

Administrative Standard of Electric Insulating Oil
Insulating Oil is dealt according to the following classifications

Normal : Available for continuous using
Caution : Needs Replacement before abnormal judgment
Abnormal : Unsuitable for using. Immediate replacement to the new insulating oil

Classification Normal Caution Abnormal
Flash Point(℃) 130≤ 126~129 T126>
Total Acid Number 0.2> 0.2~0.3 0.3≤
Corrosivity No Yes
Interfacial Tension 20≤ 19.9~15 15>
Dielectric Breakdown Voltage 30≤ 30 30>
Volume Resistivity 5×10¹¹≤ 1.0×10¹¹~4.9×10¹¹ 5×10¹¹>
Handling & Keeping of Electric Insulating Oil
The moisture content of insulating oil after purification is less than 20PPM, and it is easy to absorb moisture exposed air.
To protect decline of insulating characteristic, moisture absorption and mixture of foreign substances should be protected.
    - When fueling to the equipments, it’s inside should be clean by oil to remove moisture, foreign substances and etc.
    - Before opening the closure, clean to it’s surroundings and then do fueling.
    - It is better to refrain for handling and delivery when it is raining.
    - Keeping of Drum should be in indoor
    - Insulating oil should be used fast, not for long term keeping.
    - When filtering insulating oil, included moisture in the filter paper should be erased by well drying