# IEEE C37.66-2005 pdf free

**IEEE C37.66**-2005 pdf free.IEEE Standard Requirements for Capacitor Switches for AC Systems (1kVto38kV).

4.2.1 Abnormal ambIent temperature

Capacitor switches may be applied at higher or lower ambient temperatures than specitied in 41, but pcrtbrmance may be affected and special consideration shall be given to these applications.

4.2.2 AltItudes above 1000 m

Capacitor switches may be applied at altitudes higher than 1000 m: however, the rated lightning impulse withstand voltage, rated maximum voltage, and rated capacitive current shall be multiplied individually by a correction factors Users should consult the manufacturer for appropriate derating when the equipment is applied above 10(X) m. Annex [)can also be referred to for comments on altitude correction factors.

5. Ratings

5.1 General

When the interrupting medium is vacuwn. the capacitor switch shall withstand the rated impulse voltage in the closed position.

However, the unique characteristics of an open vacuum interrupter or vacuum gap make it permissible to have random sparkovers of the open vacuum interrupter as much as 25% below the rated terminal-to- terminal lightning impulse withstand voltage of the capacitor switch. If such an impulse surge sparks over the open interrupter contacts, the impulse current will pass through the open contacts without damage to the interrupter unit. An impulse sparkover of the open vacuum contacts may be followed by a flow of power current that will be interrupted without damage to the capacitor switches.

Switches with interrupter mediums other than vacuum shall be rated as given in Column 5 of Table I for both the line-to-ground and open gap conditions.

5.2 Rating information

Thc rating shall include the following items:

a) Raed maximum vohage

b) Rated power frequency

C) Rated peak fault-making current

d) Rated symmetrical fault-making current

C) Rated capacitivc switching current

f) Rated peak withstand current

g) Rated short-time withstand (symmetrical) current

h) Rated high-frequency transient-making current

i) Rated transient inrush frequency

j) Rated lightning impulse withstand voltage

k) Rated control voltage

1) Probability of restrike classification

5.3 Rated maximum voltage

The preferred values for maximum rated voltage of capacitor switches are shown in Column 2 of Table I.

5.4 Rated power frequency

The rated frequency of capacitor switches is 50 Hz or 60 Hz.

5.5 Rated peak fault-making current

The preferred values for the rated peak fault-making current (asymmetrical), expressed in peak amperes. are shown in Column 4 of Table 2 and Table 3 and are defined as a multiple of the symmetrical fault- making current shown in Column 5 of the tables. For switches rated according to Table 2, the multiplication factors are 2.45 for 50 Hz and 2.50 fbr 60 FIt. For switches rated according to Table 3, the multiplication factors are 2.55 for 50 Hz and 2.59 for 60 Hz.

5.6 Rated symmetrical fault-making current

The preferred values for the rated symmetrical fault-making current of capacitor switches are shown in Column 5 of Table 2 and Table 3.IEEE C37.66 pdf free download.