Voltage dip refers to a momentary voltage drop, while a blackout refers to an instantaneous power failure. They are two different phenomena. In power transmission line accidents caused by natural disasters such as lightning, a blackout can be avoided by removing short failures quickly, but a temporary voltage drop (voltage dip) cannot be avoided. Measures against the voltage dips help improve productivity significantly.


  Voltage dip Blackout
Phenomenon Voltage dip refers to the phenomenon in which the voltage drops for several cycles. It continues until a failure of a power transmission line (due to lightning, etc.) is removed from the power grid. In general, a voltage dip continues for about 0.1 seconds. Blackout refers to a phenomenon in which the voltage drops to zero for a long/short period of time. A blackout whose duration is very short is referred to as an instantaneous power failure or instantaneous interruption. Due to the use of the reclosing circuit method (in which forced line charging is conducted after recovery from insulation deterioration due to a failure of the power transmission line), a blackout continues for 10 to 60 seconds in general.


Voltage dip/blackout compensators contribute to improving the quality of the power source (measures against voltage dip and blackout).

A lineup of equipment for optimal measures to meet the needs of customers

Need Product Advantage
Measures against voltage dip(capacitor type) UNISAFE(100~400kVA)
The products compensate for only the undervoltage and are resistant to multiple lightning strikes (continuous voltage dips).
The products are highly efficient and achieve low running cost.
The products can be installed in clean rooms that are not subject to restrictions under the Fire Services Act.
UNISAFE also meets the requirements for the three-phase four-wire type SOV specifications.
Measures against voltage dip/blackout
(battery type)
The efficiency is high (99% or more).
The switching is quick at 2 msec (0.002 sec).
The product can ensure compensation for a long period of time (one minute or more).
Interconnection of power generator High Speed Fault Current limiting Switch
The product limits the fault current from the first wave using reactors.
The voltage of the power generator bus bar can be maintained until system parallel off.
The thyristor SW achieves quick parallel off of the commercial grid.

* Conform to the JIS, JEM, and JEC standards



How should I select the capacity of the voltage dip compensators (UNISAFE and MEGASAFE)?
Voltage dip compensators are series compensators. The rated capacity is indicated based on the throughput capacity. Thus, it is recommended to estimate the maximum operating capacity of the target loads and select the load capacity less than or equal to the voltage dip compensator capacity. When selecting the capacity, it is necessary to check the load current waveform. In the case of a nonlinear load such as a rectifier, the peak value is large compared to the effective current value. Please select a capacity about 1.5-fold that of the load capacity.
Do the voltage dip compensators feed power to loads other than the target load and cause undercapacity?
The voltage dip compensators are designed to compensate for the undervoltage of the power source in series. The impedance on the power source is far smaller than the impedance of the target load that is connected to the output side. The compensation voltage output from a voltage dip compensator is applied entirely to the load side to maintain the load voltage. The voltage dip compensators do not feed power to different loads that are connected to the power source side.
Are the voltage dip compensators capable of compensating for continuous voltage dips caused by multiple lightning strikes, etc.?
The voltage dip compensators are designed to compensate for the undervoltage of the power source. In the case of a voltage dip of only one phase of the three phases, the energy required for compensation is one third of that of a three-phase drop.
As discussed above, the energy stored in the power capacitor can be used effectively depending on the voltage dips generated. Thus, the power capacitor can cope with continuous voltage dips. The time required to fully charge a completely discharged power capacitor is about 40 seconds.
Are power capacitors the only power source of the voltage dip compensators?
The voltage dip compensators are designed to compensate for voltage dips only. Thus, power capacitors are the optimal power storage device. If it is necessary to compensate for voltage dips for a long period of time (e.g., blackout), please select POWERSAFE (a battery type).

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