Cart
0
Product
Products
(empty)
No products
To be determined
Shipping
$0.00
Total
Product successfully added to your shopping cart
Quantity
Total
There are 0 items in your cart.
There is 1 item in your cart.
Total products
Total shipping
To be determined
Total
Reduced price!
View larger
View larger
IEEE C37.36B
New product
IEEE C37.36B 1990 Edition, February 15, 1990 Guide to Current Interruption with Horn-Gap Air Switches
More info
Description / Abstract:
(This Foreword is not a part of IEEE C37.36b-1990, IEEE Guide to Current Interruption with Horn-Gap Air Switches.)
This guide is intended to aid air switch users in establishing suggested maximum values of excitation, resistive and capacitive currents that may be successfully interrupted while using outdoor air switches. This guide pertains to air switches mounted in the normal horizontal-upright position and not equipped with interrupting aids.
The subject of current interruption using an air switch is so common to the industry that everyone appears to have an opinion concerning this matter. Some opinions hold that an air switch should never be used to interrupt any current except the capacitive current from insulators on the shortest length of bus or miscellaneous equipment. Others can document good experiences in interrupting excitation or capacitive currents two to ten times the maximum suggested levels in this guide. Both ends of this spectrum and the variations in the middle have merit based on individual experiences. However, this guide must achieve a consensus position among switch manufacturers, engineering consultants, governmental bodies, users, and many other interested parties in order to exist. Subsequently, the suggestions in this guide have been forged upon the consensus that the current interruption levels are at least as high as the values specified herewithin. No criticism is directed toward any organization for exceeding the suggestions of this guide. Finally, this guide will continue to require feedback in the future to develop suggestions that accurately address the needs of industry.
Table 1 of this guide provides the user with a quick procedure to establish the capability of a switch for current interruption when the switch is near grounded equipment. The user should note that this procedure should only be utilized after the user has thoroughly reviewed this guide and is confident of proper application. In a similar manner, Table 2 of this guide provides the user with a quick procedure to establish the capability of a switch for current interruption when the switch is not near grounded equipment.
The user is required to calculate his or her own current interruption values for applications that differ from the assumptions of Tables 1 and 2. Refer to the Appendixes for calculation methods and sample calculations.
This guide is intended to provide air switch users with a means for determining the magnitude of excitation as well as resistive and capacitive currents that may be successfully interrupted with horn-gap, vertical-break air switches in outdoor locations mounted in the normal horizontal-upright position and not equipped with interrupting aids. The minimum centerline-to-centerline phase spacing of each switch is based upon dimensions stated in ANSIC37.32-1972 [B1]1, Table 5, Column 6. This guide assumes that the switches are applied to an effectively grounded wye system. A guide for ungrounded systems is being considered.
NOTE — Do not apply this guide to other types of switches. At this time, the confidence level for proper operation is not acceptable for other types of switches.
Use of suggestions within this guide by the air switch user should be done after proper evaluation of any adverse consequences that might result from a failure to properly interrupt the current. Adverse consequences may include phase-to-ground or phase-to-phase dielectric breakdowns, damage to other system equipment, etc.
This guide does not modify other standards such as ANSI/IEEE C37.30-1971 (Reaff 1987) [B2] or ANSI C37.32- 1972 [B1]. Therefore, the application of this guide is entirely within the domain of the air switch user. Moreover, air switch manufacturers are not required to warrant suggestions made by this guide.
This guide is intended to aid air switch users in establishing suggested maximum values of excitation, resistive and capacitive currents that may be successfully interrupted while using outdoor air switches. This guide pertains to air switches mounted in the normal horizontal-upright position and not equipped with interrupting aids.
The subject of current interruption using an air switch is so common to the industry that everyone appears to have an opinion concerning this matter. Some opinions hold that an air switch should never be used to interrupt any current except the capacitive current from insulators on the shortest length of bus or miscellaneous equipment. Others can document good experiences in interrupting excitation or capacitive currents two to ten times the maximum suggested levels in this guide. Both ends of this spectrum and the variations in the middle have merit based on individual experiences. However, this guide must achieve a consensus position among switch manufacturers, engineering consultants, governmental bodies, users, and many other interested parties in order to exist. Subsequently, the suggestions in this guide have been forged upon the consensus that the current interruption levels are at least as high as the values specified herewithin. No criticism is directed toward any organization for exceeding the suggestions of this guide. Finally, this guide will continue to require feedback in the future to develop suggestions that accurately address the needs of industry.
Table 1 of this guide provides the user with a quick procedure to establish the capability of a switch for current interruption when the switch is near grounded equipment. The user should note that this procedure should only be utilized after the user has thoroughly reviewed this guide and is confident of proper application. In a similar manner, Table 2 of this guide provides the user with a quick procedure to establish the capability of a switch for current interruption when the switch is not near grounded equipment.
The user is required to calculate his or her own current interruption values for applications that differ from the assumptions of Tables 1 and 2. Refer to the Appendixes for calculation methods and sample calculations.
This guide is intended to provide air switch users with a means for determining the magnitude of excitation as well as resistive and capacitive currents that may be successfully interrupted with horn-gap, vertical-break air switches in outdoor locations mounted in the normal horizontal-upright position and not equipped with interrupting aids. The minimum centerline-to-centerline phase spacing of each switch is based upon dimensions stated in ANSIC37.32-1972 [B1]1, Table 5, Column 6. This guide assumes that the switches are applied to an effectively grounded wye system. A guide for ungrounded systems is being considered.
NOTE — Do not apply this guide to other types of switches. At this time, the confidence level for proper operation is not acceptable for other types of switches.
Use of suggestions within this guide by the air switch user should be done after proper evaluation of any adverse consequences that might result from a failure to properly interrupt the current. Adverse consequences may include phase-to-ground or phase-to-phase dielectric breakdowns, damage to other system equipment, etc.
This guide does not modify other standards such as ANSI/IEEE C37.30-1971 (Reaff 1987) [B2] or ANSI C37.32- 1972 [B1]. Therefore, the application of this guide is entirely within the domain of the air switch user. Moreover, air switch manufacturers are not required to warrant suggestions made by this guide.