Outdoor Air Switches
Outdoor Air Switches Selection and Application 8.3 thru 800 kV Max. Voltage 600 thru 5000 Amperes
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Pascor Atlantic Air Switch Division – State Route 42
254 Industry Drive – Bland, Virginia 24315-9709 Phone: 276-688-3328 – Fax: 276-688-2228 or 2229 www.pascoratlantic.com
Selection and Application of Outdoor Air Switches Introduction Outdoor Air Switches are an essential element of electrical power transmission and distribution systems. They provide positive, visible air gap isolation of equipment and line sections for safe examination, maintenance, and repair. In the closed position, air switches must provide adequate capacity to handle all normal and abnormal currents that flow in the system. Finally, air switches must provide for ease of mechanical or electrical operation even under adverse conditions such as heavy ice coatings or corrosive atmospheres. In order to properly maintain the integrity of an electric power system, careful attention must be given to the selection and application of air switches . Insulator Cantilever Strengths Insulator stacks for any given voltage rating are available with several cantilever strength ratings such as standard strength, high strength and extra high strength. To determine which stack rating to use, it is necessary to calculate the short-circuit forces per linear foot acting on the conductors which the insulators are supporting. The NEMA formula for calculating this force is as follows:
The important considerations are:
x Insulation level to be provided. x Continuous and momentary currents to be encountered. x Insulator characteristics required. x Electrical Clearances and space limitations. x Current interrupting requirements. Air switches are built in a variety of physical forms to accommodate the various requirements of electrical clearances and limitations. Also, when used as interrupter switches, various interrupting attachments are available. Information in this publication provides a basis for selecting equipment best suited to solve most common applications. fault forces, under test conditions that are as little as 35 percent of those calculated by the equation. It is generally agreed that for outdoor substation practice, a safe multiplier to be used with the equation results is somewhere between 0.5 and 0.6. It is our standard practice to use 0.6 multiplier unless otherwise specified by the user. Further, it is our policy to limit the actual forces on the insulators to a maximum of 60 percent of their published cantilever rating. For the example given, then, a more realistic fault force is 24# x 0.6 or 14.4 pounds per foot. As noted in the bus arrangement, this force results in a maximum cantilever load of 576# at the insulator position, which supports the longest bus section. At the 115-kV rating, the published cantilever strength post-type insulator stack is 1700 pounds. When used at 60 percent of rating, the unit would have a safe allowable strength of 1020 pounds, which is quite adequate to satisfy the maximum loading required in the example. It should be noted that short-circuit loadings on switch insulators are usually less than the loadings on adjacent bus insulators, since the conductors terminate on the switch insulators and only 50% of the span applies. Notes: 1. The above applies to both upright and inverted mounted arrangements using published cantilever values. However, for insulators mounted horizontally, it is standard practice to use 40% of the upright published cantilever rating for short circuit forces. 2. If the short-circuit current (RMS asymmetrical) is not known, then the momentary rating of the switches, or the
The theoretical equation, as presented, has been found to produce fault forces on busses that are in excess of those actually experienced. Because of the inherent inertia of the bus bars, the flexibility of insulator mountings and supporting structures, some investigators have measured
breakers can be used, whichever is smaller. Switch momentary ratings are 3-phase RMS asymmetrical. Breaker ratings are 3-phase RMS symmetrical , which must be multiplied by 1.6 to convert to RMS asymmetrical
1
Selection on Basis of Insulation Level
Table 1 - Insulators
Available Insulators c Post
Ratings, kV
Insulator Technical Reference Number
Notes:
Post
Bolt Circle
Maximum Design
Nominal
BIL
For complete mechanical and electrical characteristics, contact the nearest sales representative.
Standard Strength
High Strength
3"
5"
8.3
7.2
95
202 205 208 210 214 216 286 288 291 304 312 324
222 225 227 231 267 278 287 289 295 308 316 368
8 8 8 8 8 8 8 8 8
8 8 8 8 8 8 8 8 8 8 8
15.5
14.4
110 150 200 250 350 550 650 750 900
27 38
23
d Technical Reference numbers not assigned by NEMA.
34.5
48.3 72.5 123 145 170 245 245 362 550 550 800
46 69
115 138 161 230 230 345 500 500 765
e Not available
e
1050 1300 1550 1800 2050
e e
d d e e
Switch open gap dimensions are selected to provide voltage withstand characteristics that exceed line-to-ground voltage withstand characteristics in order to protect personnel and equipment.
TABLE OF CONTENTS
PAGE
Table 2 - Switch Open Gaps
SELECTION AND APPLICATION Insulator Cantilever Strengths . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Insulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Switch Open Gaps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Ground Clearance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Phase Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Switch Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 INTERRUPTER ATTACHMENTS Arcing Horn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 Arc Restrictor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Vacuum Interrupter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 Summary of Devices and Ratings . . . . . . . . . . . . . . . . . . . . . . . 7 SWITCH OPERATING MECHANISMS MO-10 Motor Operator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8-10 Swing Handle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Worm Gear . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11 Three-Pole Torsional Control . . . . . . . . . . . . . . . . . . . . . . . . . . .11 ACCESSORIES Grounding Switches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .12 Cable Guides. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13 Auxiliary Switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 EHV Controls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .13
Min. (inches) Metal-to-Metal
Ratings, kV
Double Break One End
Single Break
Maximum Design
Nominal
BIL
8.3
7.2
95
7
NA NA NA
15.5
14.4
110 150 200 250 350 550 650 750 900
10 12 18 22 32 50 60 68 84
27 38
23
34.5
12 15 22 32 38 44 50 57 57 66
48.3 72.5 123 145 170 245 245 362 362
46 69
115 138 161 230 230 345 345
1050 1050 1300
104 104 120
Above 362 kV maximum design, switch open gap dimensions are dictated by expected maximum switching surge voltage levels.
2
Selection on Basis of Insulation Level
Table 3 - Ground Clearance
Clearance Between Overhead Conductors & Ground for Personnel Safety
Clearance Between Overhead Conductors & Roadways Inside Enclosure
Clearance to Ground for Rigid Parts
Ratings, kV
Recommended Inches
Minimum Inches
Recommended Feet
Minimum Feet
Recommended Feet
Minimum Feet
Nominal
BIL
Maximum Design
7 1/2
95
8.3
7.2
6 7
10 10 10 11 11 12 13 14 14 15 16 16 18
8 9
21 21 21 22 22 23 24 25 25 26 28 28 30
20 20 20 22 22 23 24 25 25 26 28 28 30
15.5
14.4
110 150 200 250 350 550 650 750 900
10 12 15 18 29 47
27 38
23
10 13 17 25 42 50 58 71 83 84
10 10 10 11 12 13 14 15 16 16 18
34.5
48.3 72.5 123 145 170 245 245 362 362
46 69
115 138 161 230 230 345 345
52 1/2 61 1/2 90 1/2 90 1/2 76
1050 1050 1300
106
104
Above 362 kV maximum design, electrical clearances are dictated by expected maximum switching surge voltage levels.
Table 4 - Phase Spacing
Recommended Φ to Φ Inches
Ratings, kV
Vertical Break Disc. Switch with GRD Switch
Double Side Break Disc. Switch & Bus Supports
Vertical Break Disc. Switch
Live Parts Minimum Metal-to- Metal
Single Side Break Disc. Switch
Center Side Break Disc. Switch
2500 & 3000 Amp 30° Rise
Horn Gap Switch
600 thru 3000 Amp
600 thru 2000 Amp 3" B.C.
Maximum Design
2500 & 3000 Amp 5" B.C.
Nominal
BIL
4000 Amp
8.3
7.2
95
7
18 24 30 36 48 60 84 96
36 36 39 42 48 60 84 96
36 38 42 46 50 60 84 96
40 40 44 48 52 60 84 96
18 24 30 36 48 60 84 96
30 30 36 48 60 72
30 30 36 48 60 72
36 36 48 60 72 84
d d
c c c c c c
c c c c c c
15.5
14.4
110 150 200 250 350 550 650 750 900
12 15 18 21 31 53 63 72 89
27 38
23
34.5
48.3 72.5 123 145 170 245 245 362 362
46 69
115 138 161 230 230 345 345
108 132 156 192 216 216 240
108 132 156 192 216 216 240
120 144 168 192 216 216 240
108 132 156 156 174
108 132 156 156 174
108 132 156 156 174
108 132 156 156 174
108 132 156 156 174
1050 1050 1300
105 105 119
Above 362 kV maximum design, electrical clearances are dictated by expected maximum switching surge voltage levels. Notes: c Minimum Dimension d Use Disc. Switch dimension if greater.
3
Selection on Basis of Switch Types
Table 5 – Switch Application
Switch Mounting Position
Available Interrupting Attachments
Ratings
Switch Type
IEEE Designation
Voltage, kV
Continuous Current, Amperes
Maximum Design
Nominal
Type
Ratings, kV
8.25 - 245 9 9 9 Upright Vertical
Inverted
Arcing Horns Arcing Horns
8.3 - 170 7.2 - 161 600 - 5000
1 Vertical
362 - 800 9
TTR6
245 & 362 230 & 345 1200 - 5000 Arc Restrictors
8.25 - 145 9 9 9
550 & 800 500 & 765 2000 - 4000
38 - 245
Vacuum Interrupters
9
2 Double End 2A Double End VEE 4 Side
Arcing Horns Arcing Horns Arc Restrictors Arc Restrictors Arcing Horns Arcing Horns
7.25 - 169 9 9 9 245 - 362 9 9 9 72.5 - 245 9 9 9 7.25 - 169 9 9 9 245 - 362 9 9 9 72.5 - 245 9 9 9 8.25 - 145 9 9 8.25 - 145 9 9 9 38 - 72.5 9 9 9 8.25 - 245 9 9 9
TTT7 72.5 - 550 69 - 500 2000 - 5000
TTT7-V
72.5 - 550 69 - 500 2000 - 5000
Arcing Horns Arc restrictor Vacuum Interrupters
A7
8.3 - 145 7.2 - 138 600 - 1600
8.3 - 245 7.2 - 230 600 - 3000 Arcing Horns
DR7 DR9
5 Center 6 Grounding 7 Grounding
362
345
3000 Arcing Horns
362
9
100, 120 kA Momentary 40, 61, 70 kA Momentary
AG7
8.3 - 245 7.2 - 230
None
9 9
9
None
AG8 121 - 245 115 - 230
9 9 9
8.25 - 245 9 9 9 8.25 - 145 9 9 9 8.25 - 245 9 8.25 - 245 9 9 9 8.25 - 145 9 9 9 8.25 - 245 9 9 9
Arcing Horns Arc Restrictor Vacuum Interrupters Arcing Horns Arc Restrictor Vacuum Interrupters
TTR8
8.3- 362 7.2 - 345 600 - 3000
9 Vertical Reach 10 Center VEE 8 Vertical 8A Vertical VEE
8.3 - 245 7.2 - 230 600 - 3000
TTR8-V
121 - 169 115 - 161 1200 - 4000
VT2
None
9
242 - 800 230 - 765 2000 - 4000
48.3 - 169 9 9 9
Arcing Horns
DRV 25.8 - 170 23 - 161
600 - 3000
Arc Restrictors
48.3 - 145
9
9
8.25 - 123 9 9 9 8.25 - 123 9 9 9 8.25 - 245 9 9 9 8.25 - 145 9 9 9
8.3 - 123 7.2 - 115 600 - 1200 Arcing Horns
11 Vertical
Arcing Horns Arc Restrictors Arc Restrictors
FAS3
8.3 - 245 7.2 - 230
2000
9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9
15.5 - 72.5 15 - 69
1200 Arcing Horns
15.5 - 72.5
12 Center VEE 13 Center 14 Side 15 Grounding
FAS2V
38 - 245
38 - 245 34.5 - 230 2000 Arcing Horns
15.5 - 72.5 15 - 69 15.5 - 72.5 15 - 69 8.3 - 145 7.2 - 138 8.3 - 145 7.2 - 138
1200 2000 1200 2000
Arcing Horns
15.5 - 72.5
FAS2
FAS4
Arcing Horns
8.25 - 145
40, 61, 70 kA Momentary
None
FAS-GRD 8.3 - 145 7.2 - 138
9
9 9
4
Interrupting Attachments
Arcing Horn The Arcing Horn is the simplest form of interrupting attachment. It consists of a stationary horn attached to the jaw of the switch and a movable horn attached to the blade. The purpose of the arcing horn is to avoid arcing at the main contacts of the switch during current interruption. Arc extinction is achieved by stretching out the arc. Arcing horns are used to make or break: x Magnetizing current of small transformers x Charging current of substation busses or short Transmission lines The arcing horn has been designed to require only minimum contact pressure in order to maintain minimum operating effort. Arc reach, which is the perpendicular distance between the peak of an arc and a straight line drawn between the two parting contacts (Fig. 2), should be considered for phase spacing and clearance to ground. It may be necessary to keep the arc to a minimum of 2 feet, depending upon location of equipment and recognizing environment and personnel considerations. In order to reduce the possibility of phase-to-phase faults, horn-gap switches are mounted on wider phase spacing than used for disconnect switches. For phase spacing of horn-gap switches and arc reach for various currents and voltages see Table 7.
Note: 1. Use Disc. Switch Dimension (Table 4) if greater.
5
Interrupting Attachments
Arc Restrictor The arc restrictor is an extremely effective means of interrupting transformer magnetizing and line charging currents. The arc restrictor consists of a tapered rod arranged with a latch so that it is subjected to a large deflection while the switch is opened. At a point in the opening operation when sufficient air gap has been established at the main contacts, the horn is released from the latch and travels at a very high speed, whipping out the arc. The need for very high contact speed comes about from the race between the rise of restored voltage across the contacts and the buildup of dielectric strength after current zero. If sufficient speed is attained, arcing will persist only until the first time the current in its 0-cycle excursions passes through zero. Thereafter, the moving arc restrictor contact builds up a gap of un-ionized air establishing a dielectric strength that will exceed the rise in recovery voltage so that arcing cannot recur.
Veloci-Whip Interrupter The Veloci-Whip Interrupter is an air switch attachment used to interrupt transformer magnetizing and line charging current. The Veloci-Whip is a spring-loaded high-speed whip interrupter. The enclosed spring stores energy to allow the whip to travel at a much higher rate of speed once released form the whip latch. The protective rubber boot dampens the vibration and whipping action to avoid any re-entry into the arc zone thus avoiding the opportunity for re-strike. The beryllium copper whip eliminates any curvature set over an extensive number of operations.
Because of the rapid arc extinction, switches (except the “DRV”& “FAS-2V”) equipped with the Arc Restrictor or Veloci- Whip can be mounted on disconnect phase spacing rather than horn gap phase spacing. Arc restrictors and Veloci-Whips can be mounted on vertical break or single or double side break switches. In the case of a double side break switch, two shorter rods are used, one for each separable contact.
6
Interrupting Attachments
Vacuum Interrupters Full Load Vacuum Interrupters Vacuum Interrupters are offered in (3) basic
configurations and can be attached to vertical break and side break switch designs. The configurations are as follows: A) Loop or Parallel Break – Normally these are
single vacuum contact devices, which can interrupt up to 2000 Amps, up to 230 kV, under paralleled conditions.
B) Line/Bus charging/line sectionalizing interruption/transformer magnetizing current interruption: A full voltage multiple stack interrupter may be utilized from 15kV through 230 kV for interruption of line bus charging currents and transformer magnetizing currents up to a value of 70 Amps at 0% power factor, capacitive or inductive. C) Full voltage multiple stack interrupter may be applied from 15 kV through 230 kV for interruption of actual load current at 70% power factor.
The interrupter carries load current only during the interruption. There is no external arcing, thus permitting the switch to be mounted on disconnect phase spacing. The vacuum interrupter is available for use with the type TTR8 and TTR6 vertical break switch, 38 kV through 242 kV and the type A7 single side break, 38 kV through 72.5 kV. Table 6
Summary of Interrupting Devices and Ratings
Velico-Whip High Speed Whip Line Charging or Magnetizing Currents Amperes
Vacuum Interrupter
Arcing Horns
Arc Restrictors
Ratings, kV
Maximum Permissible Arc Reach
Currents W/ Max. Permissible
Currents W/ Max. 2 ft. Arc Reach
Line Charging or Magnetizing Currents
Apprx. Charging Current
Phase Spacing (All Switches)
Maximum Design Nominal
Amperes per Mile of Line
Inches
Feet
Amperes
Amperes
Amperes
BIL
8.3
7.2
95
36 36 48 60 72 84
2 2 3 4 5 6 8 9
20 18 14 12 11
20 18 13
23 23 23 23 23 16 10
25 25 25 25 25 20 15 15 10
1/4 1/4 1/4 1/4 1/4 1/4 1/3 1/2 1/2 2/3 2/3
15.5
14.4
110 150 200 250 350 550 650 750 900
27 38
23
34.5
9 7 4 3 2 2 1 1 1 1
48.3 72.5 123 145 170 245 245 362 362
46 69
9 8 7 7 5 5 4 4
115 138 161 230 230 345 345
120 144 168 192 216 216 240
8 6
10 12 13 13 15
0.5
1050 1050 1300
1 1
7
Switch Operating Mechanisms - Electrical MO-10 Motor Operator
The MO-10 is an aluminum housed, partial revolution motor operator for actuating switches with either direct or offset torsional controls. Typical applications include remote operation of air-break disconnect switches, operation through supervisory control, or in conjunction with automatic transfer or sectionalizing schemes, or in combination with high- speed grounding switches for automatic isolation of transformer faults. The MO-10 is available with a wide range of torques and operating speeds as shown in Table 9. The voltage supply may be dc (24, 48, 125, and 250) or ac (120, 240). Because of this range of operating torque, the MO-10 may be used with Pascor Atlantic switches rated 8.3 thru 800 kV. Manual Operation The MO-10 may be manually operated by inserting the handle through the access port of the gear cover. To insert the handle, the Manual Operation Disconnect Lever must be moved to the side which electrically disconnects both motor and control circuits. Manual operation is through a 62:1 worm gear on 375:1 and 594:1 motor operators and through an 80:1 worm gear on 760:1 motor operators. Motors and Gear Drives The MO-10 motor operator is available in a variety of combinations of motors and connecting gear drive ratios see Table 8 & 9. The standard dc motor unit is rated ¾ hp, 1750 rpm and includes a 375:1 gear drive. For AC applications, the motor circuit utilizes a rectifier to convert the AC input to DC. Dynamic Braking is accomplished through a braking resistor in the DC motor circuit. Other combinations of motor rating and gear drive assemblies are tailored to satisfy specific output torque and/or speed requirements. All motors have high starting and running torques at minimum IEEE voltages, are sealed against moisture, dust and fumes, and require no lubrication. The motor circuits are protected by class cc fuses, which permit locked armature current flow for a short period.
8
Switch Operating Mechanisms - Electrical
MO-10 NG Design Features
Overview The MO-10NG motor operator is a state of the art design utilizing Programmable Logic Controllers (PLC) to provide a variety of configurable options. A Human Machine Interface (HMI) screen provides reliable, secure and straightforward configuration of the MO-10NG. The MO-10NG includes a wide range of functions that can be configured prior to shipment or in the field through the menu screen of the HMI. The features include:
x Voltage Options of 24, 48, 125 & 250 VDC and 120, 240 VAC x Pushbuttons (Open, Close and Stop) x Local and/or Remote operation x Operation time delay and counter x Six custom outputs x Positive electro-mechanical Open and Close limit switches
x Open and Close speed control x Watch Dog condition monitoring
Open and Close Speed Control EHV disconnect switches can exhibit blade bounce at the end of an open or close operation due to the length of the blade and operating time of traditional motor operators. The MO-10 NG code incorporates a speed control menu that allows for four separate open and close sectors that are variable in duration. Motor speed can be set between 5 and 100% in each of the sectors. Utilizing the variable sectors and range of motor speed allows for control of the switch blade throughout its travel and virtually eliminates blade bounce. Watch Dog Condition Monitoring Condition monitoring is achieved by capturing motor current and operating time measurements. Once the MO-10NG and associated disconnect switch have been adjusted, the motor current and operating time can be archived. All subsequent operations are then compared to the archive data. A trending screen is also incorporated on the HMI screen which shows the last open and close operation as well as the motor current. Increases in the motor current and operating time are key indicators that a switch requires maintenance. The data obtained can be easily downloaded from a USB port on the HMI. In addition to the motor current and operating time the date and time of each operation is also recorded. Once saved to a flash drive, the data can easily be imported into an Excel spreadsheet.
1
HMI Home Screen
HMI Operations Screen
9
Switch Operating Mechanisms - Electrical
Table 7 – Motor Mechanism Selection
Switch 15 - 345 kV Motor Mechanism Item
8.3 - 170 kV (except 1000 A TTR6 Vertical) 15 - 345 kV 4000 A TTR6 Vertical Break
1,4
2
2
245 - 362 kV
3
550 kV Vertical Break
362 kV TTR8
6
362-500 kV Multi Rev
7
Table 8 – Technical Data, Mechanism
Oper. Time 190° Travel Seconds Normal Service Conditions
Vertical Operating Pipe
Motor Mechanism Item
Motor
Torque In-lb
Gear Ratio
HP
RPM
SPS Min.
Feet Max.
2
30 60 30 60 30 60 30 60
3450
22,000
375:1
3.4
4
3/4
2 1/2
2
3450
30,000
594:1
5.4
5
3/4
2 1/2
2
6.8
1750
22,000
375:1
1
3/4
2 1/2
2
10.8
1750
30,000
594:1
2
3/4
2 1/2
3
34,000
13.7
3 x HVY
20
1750
760:1
3/4
2
30 60 30 60
6
30,000 3/4
1750
760:1
13.7
2 1/2
2
7
8,000
3/4
3450
48:1
14.0
2 1/2
Table 9 – Technical Data, Motor
Current, Amperes
Operating Voltage Range
1750 3450 1750 3450 1750 3450 1750 3450 Rated Speed
Fuse Size Type CC Time Delay
Rated Voltage
Rated HP
Locked Armature
Rated RPM
3/4 3/4 3/4 3/4 3/4 3/4 3/4 3/4
30 30 14 14
211 306 106 203
30 30 30 30 10 10
24
20-28
48
36-56
DC
5 6 3 3
42 61 25 35
125
90-140
6 6
250
180-280
10
Switch Operating Mechanisms – Manual
Description A switch operating mechanism is a means for opening or closing a group operated air switch and occasionally a single pole switch, from a fixed position, usually at ground level. Forces are transmitted from the operator’s position to the moving parts of the switch. The two most commonly used operators are torsional (swing handle) and worm gear types. Swing Handle The swing handle is a manually operated torsional mechanism, which is hinged to the vertical operating pipe. Two lengths of handles are available. A three-foot handle and a five-foot telescopic handle. The swing handle is actuated by raising the handle to a position parallel to the ground followed by a direct horizontal lever action applied to rotate the vertical operating pipe. The three-foot handle is used primarily for switches rated 8.25 thru 72.5 kV. The five-foot handle is used for lower voltages where additional operating effort is required by accessories or for higher voltage switches 121 thru 170 kV.
Worm Gear The worm gear is a manually operated torsional mechanism. It is recommended for operating tree-pole switches requiring increased operating effort depending on switch type, ratings and interrupter attachments. The worm gear is a corrosion free mechanism consisting of a 15-inch crank handle and weather sealed gearbox. It is available in gear ratios of 46:1, 62:1, 80:1 and is especially designed to prevent backlash.
Three-Pole Torsional Control Operating Mechanism
A three-pole torsional control can be activated by a simple swing handle, a worm gear or a motor operator depending on torque required. Offset Bearing Same as the switch bearing with two sets of stainless steel ball bearings, weather-sealed and maintenance free. Multi-Angle Crank Switch and controls can be relocated to different structures and different offset angle with no change in parts.
1 0
11
Accessories
Grounding Switches
FAS-GRD, AG7 and AG8 grounding switches can be applied on either the hinge or jaw end of most switches for grounding lines on equipment during inspection, maintenance, or repair. The 3- pole grounding switch is frequently interlocked with the main switch on which it is mounted, to prevent both switches from being closed at the same time. Grounding switches can also be supplied with their own separate base and insulator stack rather than attached to a disconnect switch. Grounding switches must be designed, built and tested to withstand the rigors of associated equipment, high momentary ratings, ice-breaking ability, and wind-loading resistance.
High-Speed Grounding Switches (Automatic)
Automatic high-speed grounding switches provide the most economical means of transformer protection. Their application has become well accepted at the result of the excellent reliability of modern transformers, extremely fast relay and circuit breaker operation, and last but not least, dependable design. The purpose of the high-speed grounding switch (HSG) is to create deliberate fault upon a signal from the protective relays of the faulted transformer. Fault current relays trip the remote circuit breaker. With high speed components used in the scheme, a transformer is de-energized with a few cycles after it develops an internal fault, thus limiting costly transformer damage. Since the HSG is a fault-initiating device, it is normally supplied for single pole operation; however, 3-pole operation can also be supplied. It can be reset with either a hook stick or an operating handle at ground level.
The HSG switch can be supplied in these forms: x On any non-rotating insulator of any switch. x As a complete unit with its own base and insulator.
12
Accessories
Cable Guides (Outriggers)
Auxiliary Switch
The frequent need for remote switch position indication, electrical interlocking of main and ground switches with each other or with breaker controls and other operating sequences, requires the application of auxiliary switch units to switch operating mechanisms. These separately mounted devices are available in multi-stage circuits from 2 thru 16, in multiples of two stages. Auxiliary switches are totally enclosed in weatherproof housings, which provide entrance openings for termination of conduit.
Cable guides or outriggers are fabricated of either extruded T-sections or tubular bus. Both versions are high conductivity aluminum and bolt directly to the switch terminal pad, on either the hinge or the jaw end. The outer end of the outrigger has a NEMA standard 4-hole terminal drilling. Cable guides are used to support the cables well away from the switch base and grounded parts. They are designed for a 100-pound maximum downward force at their outer end. Standard lengths are 2, 3, and 4 feet from insulator centerline to the outer end of the cable guide.
EHV Controls
The GTS is a superior design to other operating mechanisms for EHV switches that will reduce your crew time and dramatically decrease overall project costs. The GTS is a design concept that has been accepted in the air disconnect market for 50 years. A 65% parts reduction results in greatly reduced assembly and adjustment time. It will operate switches up to 500kV and 5000 amps. The GTS has been through rigorous mechanical operational tests enduring over a 4-month period and performed more than 5,000 operations. The GTS is a multi-revolution design with an operation time of 14 seconds. The drive insulator rotates on a maintenance free 30:1 worm gear rotor bearing assembly (Figure 1). The housing is comprised of high strength aluminum alloy castings including three sets of stainless steel bearings. A 1:1 ratio type “T” gearbox is used to transfer the vertical load to a horizontal load. The gearbox is constructed of stainless steel shafts enclosed in an aluminum housing (Figure 2). Interphase shafts connect to the rotor bearing under each pole. The heavy duty coupling (Figure 3) is designed to simplify the adjustment process. Each pole is symmetrical which allows the operator to be mounted on any of the 3 phases. The GTS is a competitive product and is another example of how Pascor Atlantic responds to customer needs. It is recognized that crew installation time is a substantial cost to an overall project. The GTS in actuality reduces budgeted installation and adjustment time by 50%.
Figure 1
Figure 2
Figure 3
13
Testing
At Pascor Atlantic we test beyond IEEE requirements, from mechanical testing, electrical testing, and environmental testing we exceed the standard. In house, we have the capabilities of conducting various tests. Temperature Limitation can be tested in house, measured through thermocouples and collected for reports. Mechanical Operation tests are administered and exceed the recommended 1000 operations with greater than 10% of those with terminal loading per IEEE standards. Environmental Testing such as ice, wind and contamination are conducted and the results are recorded in every test report where applicable.
Other testing such as Seismic, Dielectric and Short- Circuit, that is beyond our capabilities is tested at various third party labs and results observed by and reported directly to Pascor Atlantic.
Rest assure that every switch produced at the factory is tested for operation and resistance and recorded for that specific order. Every Motor Operator is tested for operation and function prior to shipment and recorded for that unique design.
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Delivering More... Delivering Service
Pascor Atlantic Air Switch Division – State Route 42
254 Industry Drive – Bland, Virginia 24315-9709 Phone: 276-688-3328 – Fax: 276-688-2228 or 2229 www.pascoratlantic.com
This bulletin describes our standard product and does not show variations in design, which may be available. If additional details are required, contact your local Pascor Atlantic representative. Pascor Atlantic reserves the right to make changes and improvements to the products shown in this bulletin without notice or obligation.
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