Ratings for Vacuum Electric Switches

Design VoltageNominal/Maximum (kV) 15/15.5 34.5/38 46/48.5 69/72.5
Continuous current( RMS Amperes) 6005 6005 300 6004, 5 300 300
Fault Interrupting Current( RMS Amperes) Max. 4000 4000 3000 4000 3000 3000
Momentary Current(RMS Amperes, Asymmetric) 20,000 20,000 15,000 20,000 15,000 15,000
Frequency (Hz)3 50/60 50/60 50/60 50/60 50/60 50/60
Two-Second Current(RMS Amperes) 12,500 12,500 12,500 12,500 12,500 12,500
Four-Second Current(RMS Amperes) 9000 9000 9000 9000 9000 9000
Impulse Withstand, Terminal-to-Terminal (kV)Line-to-Ground (1.2 X 50 Positive Wave) 1101/150 2001/200 2001/200 2001/250 2501 2801/350
Maximum 60-Cycle WithstandLine-to-Ground (kV)One Minute Dry

Ten Seconds Wet

101
74
138
119
138
119
178
176
178
176
245
198
Maximum Peak Inrush Current (RMS Amperes) 20,0002 20,0002 15,0002 20,0002 15,0002 15,0002

1The terminal-to-terminal BIL is not established by a visible open gap and therefore cannot be used to establish safety clearance for personnel.

2 When switches are used for capacitor bank switching, restrike probabilities are determined by the magnitude of the in-rush current, the contact open gap, and the contact material.  This is explained in a Toshiba paper found in IEEE Transactions  on Power Delivery Vol 10, No. 2 April 1995.  Using reactors to reduce in-rush current reduces restrike probability.  In back-to-back capacitor switching peak currents should be limited by reactors to a switch’s fault interrupting rating.  The contact material used in these switches is copper tungsten the same as reported to have the lowest restrike probability in this Toshiba paper.  In aged switches with high operation counts contact welding may occur if the in-rush currents are not limited.

3Switching a harmonic filter requires special considerations.  Consult the factory about these applications.

4For capacitor bank switching only, this switch is limited to being used on solidly grounded systems

and solidly grounded capacitor banks with currents of less than 200 amperes.

5When switches are used in parallel, the continuous current rating is reduced to 500 amperes to account

for unequal current distribution between switches.

6When switches are used for capacitor bank switching, restrike probabilities are determined by the magnitude of the in-rush current, the contact open gap, and the contact material.  This is explained in a Toshiba paper found in IEEE Transactions  on Power Delivery Vol 10, No. 2 April 1995.   Using reactors to reduce in-rush current reduces restrike probability. The contact material used in these switches is copper tungsten the same as reported to have the lowest restrike probability in this Toshiba paper.