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The home and office digital appliances such as PCs, copiers and printers all use capacitor type power suppliers for voltage stabilization, and noise eliminators or filters. In addition, the increased scale of electric cables and increasing capacitance between cable and ground, lead to increased leakage current toward ground. The present situation is that earth leakage breakers (Io ELB) do not properly operate and in order to find the cause of leakage or the malfunction of the breaker, all the equipments must be unplugged and measure the insulation resistance with the Megger tool. In actual, it is very difficult or even impossible to shut down the equipments and use the Megger to measure insulation resistance and even if tested this way, there will be a lot of waste in personnel and cost because the equipments must be fully powered off.

The ELB(Earth Leakage Breaker) is also called as RCD(Residual Current Device) and GFCI(Ground Fault Circuit Interrupter).

The inverters, which are widely used in washers, air conditioners, elevators etc due to their energy efficiency and detail control function, cause a lot of harmonics leakage current. This leakage current may flow through the wires of the building and thus cause malfunction to the connected appliances.

In the control rooms of factories, substations, IDC center powered from UPS, a large amount of leakage current is released and most of the time, the conventional leakage breaker(Io ELB) cannot handle the leakage and thus malfunction. Therefore, in most control rooms the leakage breaker(Io ELB) is either taken away or even never installed from the beginning, thus install MCCB instead of ELB. This is a very dangerous situation as resistive leakage current can lead to fire in these facilities.

The earth leakage breakers(ELB) operates based on Io(I zero), and therefore in the digital world of today, the breakers does not function properly in world-wide.

Therefore, our company has developed an IGR leakage breaker which can operate at the amount of resistive leakage current properly, but will not operate at capacitive leakage current properly. The innovative IGR breaker will operate more sensitively to effective factor of resistive leakage current than to non-effective factor of capacitive leakage current.

IGR Leakage Analyzing technology　
The concept of ground connection and Insulation resistance and ground capacitance.

Ground Insulation Resistance	Ground Capacitance
The effective leakage current that flows from the ground insu lation resistance of appliances also known as IGR. If the IGR, which directly affects the insulation resistance of the leaka ge current, can be powered-off, the insulation status of the circuit can be analyzed.	The leakage current involved with ground capacitance is known as IGC and if the circuit connected to the transformer is long away, IGC will be larger than IGR. There is a 90° difference in phase between the IGR and IGC and the vector sum is called Io(I zero).

The need for Igr leakage measurement.
: The Io, which is the leakage current measured by Zero Current Transfomer(Zct) is the vector sum of Igr (insulation Resistive leakage) an dIgc (capacitive leakage).
Therefore Igc flows naturally on normal power line, main task in handling insulation resistance is to manage the effective leakage curren t, Igr.

If the electric cables are inside a duct or underground conductor, cable inspection may be impossible.
Therefore, in order to accurately inspect the cable status, a speci al measuring instrument must be used.

In the past, the insulation resistance was measured on a dead-line, but nowadays there are man y appliances which need to operate 24 hrs a day and therefore technologies which can measure leakage current on a live-line is continu ously being developed.

The following diagram shows that the actual calculated value matches the measured value.

SW	Resistance	Leakage Current Igr
SW1 and SW4	20㏀	10㎃
SW2 and SW4	40㏀	5㎃
SW3 and SW4	10㏀	20㎃

The following diagram helps to understand the vector disintegration formula.

SW	SW usage	Leakage Current
SW1	Rø Io = Igr ( = Igc)	10㎃
SW2	Rø Io > Igr	5㎃
SW3	Rø Io < Igr	20㎃
SW4	Rø Igc	10㎃
SW5	Tø Io = Igr ( = Igc)	10㎃
SW6	Tø Io > Igr	5㎃
SW7	Tø Io < Igr	20㎃
SW8	Tø Igc	10㎃

- Rø or Tø

SW	Resistance	Leakage Current (Igr)
SW1 or SW5	20㏀	10㎃
SW2 or SW6	40㏀	5㎃
SW3 or SW7	10㏀	20㎃

- Rø and Tø

SW	Resistance	Leakage Current (Igr)
SW3 and SW6	10㏀ and 40 ㏀	25㎃
SW1 and SW5	20㏀ and 20 ㏀	20㎃
SW2 and SW7	40㏀ and 10 ㏀	25㎃

- (Rø or Tø) and C

SW	Resistance	Leakage Current (Igr)
(SW1 or SW5) and (SW4 or SW8)	10㏀ and 40 ㏀	25㎃
(SW2 or SW6) and (SW4 or SW8)	20㏀ and 20 ㏀	20㎃
(SW3 or SW7) and (SW4 or SW8)	40㏀ and 10㏀	25㎃

The advantage of Igr leakage detection using phase difference measurements as our patented technology.
- The calculated value matches the measured value.　
- The Igr measuring using the frequency injection method can be erroneous in modern appliances such as inverters and PC due to the harmonics and noise zone.
- However, the Igr leakage measuring technology calculates the voltage of power line and phase difference. Thus, the actual leakage current (Igr) can be accurately calculated without turning off the power.
- Years of research showed that the measured value is reliable and on-site experiences of the technology proved the measurements to be accurate.

DalZiel Data
In 196, Dalziel carried out a research about the lethal amount of leakage current to human electrocution and the results are as follows.

[LETHAL ELECTRIC CURRENTS IEEE Spectrum, Vol. 6, pp. 44-50]

Therefore the US Leakage Breaker(UL943 Class A)’s for human protecting tipping point is set at 6mA±1mA.

IEC (The required standard of electric safety measures of data communication equipments forwarded by IEC60950/UL60950. Leakage current must be kept below the followingvalues).
- Class II (without ground connection) 0.25㎃ → at 220V about 0.88MΩ
- Class I (with ground connection) 0.35㎃ → at 220V about 0.63MΩ

Intended Achievements
Igr control plans leading to lower risk of accidents and increased