ENERPIA
The cutting-edge technology of ENERPIA leads to a richer life.
The cutting-edge technology of ENERPIA leads to a richer life.
Withstand voltage test
Withstand voltage is the maximum voltage that can be applied on the insulator without destroying insulation. Withstand voltage test evaluates presence of insulation destruction when applying a preset voltage.
[Caution] Since excessive withstand voltage test may give potential damage on the insulator, increasing the risk of accident after shipment, appropriate test voltage must be set by product.
Calculation of testing voltage for AC withstand voltage
The following equation is mainly used. If there are regulations in SPEC, SPEC regulations are used.
AC testing voltage (VAC) =2 x (AC voltage used) + 1,000
If voltage used is AC 220V, the testing voltage for AC withstand voltage is VAC = 2 x (220) + 1,000 = 1,440(V). Since testing voltage is normally set in the unit of 100V or 500V, the testing voltage is 1,500V(1.5kV). Testing period for withstand voltage is 1 minute in general.
Calculation of testing voltage for DC withstand voltage
DC testing voltage is different from that of AC. General Equation for DC testing voltage is as follows.
AC 220V refers to AC 220V(RMS). Since Peak value must be 1.414 times (=√2), the result is AC 317V(V).
VPEAK = 1.414 x VRMS
Therefore, when the withstand voltage test is performed with a DC voltage, the AC test voltage should be 1.414 times.
DC testing voltage (VDC) = 1.414 x VAC = 1.414 x {2 x (AC voltage used) + 1000}
If voltage used is AC 220V, the testing voltage for DC withstand voltage is VDC = 1.414 X {2 X (220) + 1,000} = 2,136(V).
Since testing voltage is normally set in the unit of 100V or 500V, the testing voltage is 2,500V.
Insulation Resistance
When applying DC voltage on insulator, an extremely small amount of electric current flows.
The ratio of this current and the voltage applied is called insulation resistance.
Small value of insulation resistance means that there is a high risk of leakage due to deterioration or damage of electric cable.
Characteristics of insulation resistance
If temperature characteristic is minus
– Measurements of insulation resistance of the same electric cable may change depending on the temperature of the insulator at time. When temperature rises, insulation resistance becomes smaller.
If voltage characteristic is minus
– Insulation resistance is measured to be small with higher voltage measured.
When moisture absorption occurs, insulation resistance is greatly reduced.
Dielectric strength
When the voltage is gradually increased on the insulator in order to reach a certain voltage, a large current suddenly flows, making the part conductive. This is called dielectric breakdown, and the voltage at this point is called dielectric breakdown voltage. The value where this voltage is divided by the thickness of the insulating material is called dielectric strength (kV/mm).
– Dielectric strength increases with higher insulation thickness
– Dielectric strength decreases with higher temperature of use
– Dielectric strength decreases with higher frequency of use
– Dielectric strength decreases with higher humidity
Unit of insulation resistance [MΩ•km]
MΩ•km is insulation resistance for 1 km of electric cable.
When the length of the electric cable increases, the number of routes for leaked electric current increases, reducing insulation resistance.
(Ex) For electric cable with insulation resistance of 50MΩ•km,
– Insulation resistance of electric cable with length 1 km = 50(MΩ•km)/1(km) =50(MΩ)
– Insulation resistance of electric cable with length 5 km = 50(MΩ•km)/5(km)=10(MΩ)
R20=Rt*Kt*L/1000
R20: Insulation resistance (MΩ•km) converted to 20℃, 1km
Rt: Measurement value (MΩ) at t℃. If resistance value of lead cable is included, the value that excludes the resistance value.
Kt: Temperature conversion coefficient that converts the value of measurement temperature t℃ to 20℃
L: Length of electric cable (m)
Measurement method
Withstand voltage test
– Completed goods shall withstand AC 2.5kV x 1min. in the air
– Insulation cable shall withstand AC 5.0kV x 1min. in water
Measurement of insulation resistance
– For completed goods, measure after DC 500V x 1min. in the air
– For insulation cable, measure after DC 500V x 1min. in water
Order of testing: Withstand voltage test → Measure insulation resistance
Conductor Resistance
When applying direct voltage on a conductor, electric current flows on the conductor.
At this point, the direct voltage that has been applied and the electric current that is flowing are in a proportional relationship.
The proportional constant is called electric resistance, and electric resistance represses the flow of electric current.
Equation for calculating conductor resistance
Equation for correcting conductor resistance measured at external temperature t(℃) using temperature condition of 20℃
R = L / (58xSxC)
R = Conductor resistance (Ω)
S = Area of conductor cross-section (mm2)
C = Conductivity of the conductor (1.0 for annealed copper wire)
If conductor resistance measured at 15℃ is 18Ω, conductor resistance corrected to 20℃ is R20 = 18 x 1.02 = 18.36Ω.
R20 = Rt x α
R20 = Conductor resistance (Ω) corrected to 20℃
Rt = Conductor resistance (Ω) measured at t℃
α = Temperature correction coefficient
t = External temperature (℃)
Temperature correction coefficient
Measurement temperature | Correction coefficient | Measurement temperature | Correction coefficient | Measurement temperature | Correction coefficient |
---|---|---|---|---|---|
t ℃ | α | t ℃ | α | t ℃ | α |
1 | 1.082 | 15 | 1.020 | 29 | 0.965 |
2 | 1.078 | 16 | 1.016 | 30 | 0.962 |
3 | 1.073 | 17 | 1.012 | 31 | 0.958 |
4 | 1.068 | 18 | 1.008 | 32 | 0.954 |
5 | 1.064 | 19 | 1.004 | 33 | 0.951 |
6 | 1.059 | 20 | 1.000 | 34 | 0.947 |
7 | 1.055 | 21 | 0.996 | 35 | 0.943 |
8 | 1.050 | 22 | 0.992 | 36 | 0.940 |
9 | 1.046 | 23 | 0.988 | 37 | 0.936 |
10 | 1.042 | 24 | 0.984 | 38 | 0.933 |
11 | 1.037 | 25 | 0.980 | 39 | 0.929 |
12 | 1.033 | 26 | 0.977 | 40 | 0.926 |
13 | 1.029 | 27 | 0.973 | ||
14 | 1.025 | 28 | 0.969 |
UL
– UL (Underwriters Laboratories Inc.) is a major certifying institution in USA which has provided standard development and certification services on product safety since its foundation in 1894.
– UL standard is used as the safety standard in USA. Since the reliability of UL is high in USA and it is highly preferred by consumers, it is essentially a forced standard that is required for exporting to USA.
– Relevant regulations: Technology standard UL, ASTM, ASME, ANSI, etc.
– Target items: Electronic appliances, refrigerating air handling units, industrial control devices, firefighting devices, audio/video, medical/measurement devices, electrical wire and cable, information communication devices, plastic, EMC, etc.
CSA
– CSA (Canadian Standards Association) is a non-profit private organization which was established for safety of Canadian citizens, and benefits of the government and industries. It writes standards and provides testing and certification services.
– Items with risks, such as electrical devices and gas combustion devices, are forced standards, and items that do not have risks, such as quality management, are recommended standards.
– Relevant regulations: Canadian Electrical Code
– Target items (forced regulation): Electrical devices, electrical machines, electrical cables, electrical parts, materials and gas, petroleum or gas combustion devices, etc.
cUL
– cUL refers to works of testing, certification, quality evaluation, and registration services by UL on Canada-bound products.
– cUL mark is given to appropriate products after testing according to CSA standards.
– Its difference with CSA mark is that the certifying institution is either UL or CSA. For both marks, testing is conducted according to CSA standards.
Types of UL mark
Listing Mark: Applied on products that can be directly purchased by consumers in the market
Recognized Component Mark: Applied on parts and partial products
Classification Mark: Applied on products with specific risks or standards, such as fire door
UL No. (electric cable for devices, AWM)
Style No. | Material | Number of cores | Product |
---|---|---|---|
1001~1999, 10000~ |
Thermoplastic insulation cable (Thermoplastic) ex: Teflon, PVC, PE, etc. |
Single-core | •Heat-resistant vinyl electrical cable •Fluorine resin electrical cable •Coaxial cable |
2001~2999,
20000~ |
Thermoplastic insulation and jacket (Thermoplastic) ex: General PVC, PE |
Multiple-core | •Computer Cable •Flat Cable •Cord, Feeder |
3001~3999 | Thermosetting insulation cable (Thermosetting) ex: Silicone, XLPE, etc. |
Single-core | •Silicon wire • Rubber electric cable such as silicone cable •XLPE. XLPVC, etc. |
4001~4999 | Thermosetting insulation and jacket(Thermosetting) ex: Silicone, XLPE, etc. |
Multiple-core | •Multiple-core rubber wire •Multiple-core XLPE electric wire, etc. •XL-Flat Cable |
5001~5999 | Special items | Single-core / Multiple-core | •Mica, • Optical fiber cable for devices, etc. |
CE(EMC)
– Country: EU, Turkey
– Used on devices that cause electromagnetic disturbance or those that may be affected by such disturbance
– In order to acquire this mark, devices must be produced as follows.
(a) The electromagnetic disturbance produced shall not exceed the level where radio wave, remote communication, or other cases that meet the intention of using the device, and
(b) The device shall have appropriate level of unique immunity on electromagnetic disturbance in order to be operated as the original intention.
– Relevant regulations: Guidelines on electromagnetic wave (2004/108/EC)
– Target items: Devices that cause electromagnetic disturbance or those that may be affected by such disturbance.
CCC (Electric safety)
– Country: China
– CCC forced product certification policy is a product passing policy based on the legislations and regulations of the Chinese government for protecting the safety of consumers, animals, and plants, protecting nature, and protecting national safety.
– Products under the policy of forced product certification must comply with the standards and technological regulations of China. Forced products must acquire certificate after receiving testing from testing agencies designated by CNCA, other than CQC, and receiving factory institution by inspector from a designated certifying agency. Products that fail to acquire certificate by certifying institution or those that do not attach certification mark according to regulations may not be used for import, customs, shipment, and activities in the business market.
– Target items: Electric cable parts, cables for railroads and vehicles below alternating 3KV, rubber insulation cable below 450/750V, PVC insulation cable, parts for fixed electric devices for household use and similar use, etc.
EAC(Electric safety)
– Country: CU (Tariff alliance)
– EAC mark certification of CU(Customs Union) was created by integration of GOST-R(Russia), GOST-K(Kazakhstan), and STB(Belarus), which had been used independently by Russia, Belarus, and Kazakhstan.
– As of February 15, 2013, electrical and electronic products that are distributed within the three countries with the rating of AC50-1000V, DC75-1500V can be exported only if they have CoC or DoC according to technological regulations regulated by CU.
– Items subject to CoC in terms of technological regulation must receive CoC. Electrical or electronic products that are not subject to CoC but are operated in AC50-1000V, DC75-1500V must receive DoC.
– While product testing for CoC must be conducted at a designated test site in principle, multiple certifying agencies are issuing certificate by accepting CB/CE Safety report without additional testing. For consecutive certification (with period of effectiveness of 1-5 years), factory inspection is conducted as well.
– Relevant regulations: CU TR 004/2011(On safety of low-voltage equipment)
– Target items: Electrical and electronic products, home appliances, personal computers, low-voltage devices connected to computer, manual portable electrical devices, electrical instruments, cables, electric cables, cords, circuit breakers, shutdown protection devices, electric energy distributors, and electric facility controllers, all of which have rating of AC50-1000V, DC75-1500V
TÜV
– TÜV(Technical Control Board) is a government-certified inspection agency of Germany. It is in provincial areas of Germany, such as TÜV Rhineland and TÜV Bavaria.
– Almost all organizations with public nature, such as the German government, are inspected by TÜV. TÜV has the characteristics of an independent, third-party inspection agency. The stringency of its inspections and the high technical level of its employees are well-known not only in EU but also around the world.
PSE
– PSE certification is a forced certification that is conducted in accordance with the Japanese Electrical Appliances Safety Act. It aims to regulate production, sales, etc. of electrical appliances and to minimize harms and damages regarding ensuring safety of electrical products.
– Those who are producing electrical products for exporting them to Japan or those who are selling such products by importing them must meet the technical criteria for the products, and must indicate PSE mark accordingly.
– Items subject to certification are classified into specified products (116 items) and non-specified products (341 items). The procedure and requirements of certification vary by the two classifications, and the type of the PSE mark varies accordingly as well.
– Target items:
1. Specified Products (SP): Electric cables, wiring devices (switch, circuit breaker, plug, joint box, etc.), heating devices (electric toilet seat, heating cabinet, water heater, sauna, heater, etc.), etc.
2. Non-Specified Products (NP): Conduit, small-sized AC motor, heating devices (most heating devices such as foot warmer, electric cushion, electric blanket, hand warmer, oven, and rice cooker), etc.
PSE
– Korea Certification Mark
– A certification mark which unifies certification marks in each area, such as safety, health, environment, and quality. Currently, there are around 70 legally mandatory certification policies in Korea.
– Products subject to KC mark are around 730 products including automobiles, electronic products, strollers, elevators, lighting devices, scales, electronic scales, telephones, and fire extinguishers.