Vacuum Circuit Breaker (VCB)

The high-voltage vacuum circuit breakers are designed and manufactured in accordance with latest IEC standard, IEC 60056, IEC 2300, and for indoor switchgear purposes. The circuit breakers shall be applied according to normal service conditions specified. Please consult other than normal service conditions.

Normal Service Conditions

  1. The ambient air temperature does not exceed 40°C and its average value, measured over a period of 24 h, does not exceed 35°C.
    The minimum ambient air temperature is -5°C for class "minus 5 indoor".
  2. The altitude does not exceed 1,000m.
  3. The ambient air is not significantly polluted by dust, smoke, corrosive or flammable gases, vapors or salt.
  4. The average value of relative humidity, for a period of 24h, does not exceed 95%.
    The average value of relative humidity, for a period of one month, does not exceed 90%.
    No condensation can be expected where sudden temperature changes occur in periods of high humidity.

Special Service Conditions

Do not install the circuit breakers in areas where special service conditions exist. Using this equipment in other than normal service conditions can results in equipment failure.

Precaution

Do not exceed the ratings specified on the equipment nameplates or system accessories.
The supply voltage of auxiliary circuit shall be value shown in following table.

Precaution List

Precaution List
Operating method Voltage Allowable voltage range
Operating voltage Closing voltage Case of operating/control combined Opening voltage
Motor spring DC 85-110%
of rated voltage
75-125%
of rated voltage
75-110%
of rated voltage
60-125%
of rated voltage
AC 85-110% of rated voltage

Application for Surge

The insulation coordination shall be evaluated with following table.

Application for Surge List

Application for Surge List
Category of VCB Loads
Motors
(*1)
Oil-Immersed transformers
(*2)
Molded transformers
(*2)
Dry type transformers
(*3)
7.2kV Low surge type VCB
(*4)
Not required
(*6)
Not required Not required Not required
(*7)
7.2kV Conventional VCB
(*5)
Use surge suppressor Not required
(*7)
Not required
(*7)
Use arrester
12kV VCB Use surge suppressor Not required
(*7)
Not required
(*7)
Use arrester
24kV VCB -
(*8)
Not required
(*7)
Not required
(*7)(*9)
Use arrester
36kV VCB -
(*8)
Not required
(*7)
Not required
(*7)(*9)
Use arrester
  • *1 Besides induction motors,synchronous motors or generators are included in this category.
  • *2 Transformers, having insulation strength mentioned in the following table(*), are applicable.
  • *3 Dry type transformers, having insulation strength mentioned in the following table(*), are applicable.
  • *4 Toshiba Vacuum Circuit Breakers type "V4AS-" , "V6AS-" , "V4BS-" , "V6BS-" , "VHA-" , are the low surge type.
  • *5 Hereupon the Vacuum Circuit Breakers except "Low Surge Type VCB" are called "Conventional VCB".
  • *6 For small motors (such as 55kW at 3.3/6.6kV, 300kW at 11kV, 5.5kW at low-voltage or below) and/or to be subject to inching operation, the protection with surge suppressor is required.
    The switching of machine of extraordinary low insulation level, the protection with surge suppressor is required.
  • *7 For transformers which are subject to exciting inrush current interruption, protection by arresters is required.
  • *8 Not applicable because of no experience for this rated valtage.
  • *9 For transformers subject to frequent load current switching , protection by the arresters is required.
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