A New Electrical Research Laboratory F. E. ANDREWS ALEX VITKUS

F E L L O W A I E E M E M B E R A I E E

The research laboratory described is a compre­hensive facility, capable of duplicating system operating conditions. Its principal function is the development and engineering of electrical and line construction products for power trans­

mission and distribution systems.

THE POSTWAR DEVELOPMENT of electric power systems has been characterized by increas­ingly severe requirements of electric apparatus

in terms of large short-circuit currents and high volt­ages. T o fulfill the industry's needs for improved equip­ment to meet these new requirements, and to provide facilities for general research and testing in this field,

F i g . 1. O v e r - a l l v i e w o f l a b o r a t o r y .

Hubbard and Company placed in operation during 1958 a new electrical research laboratory at McCook, 111., near Chicago. This laboratory is a fully integrated facility, capable of duplicating system operating condi­tions, where both electrical and line construction prod­ucts for power transmission and distribution systems and for wire communication systems can be developed from the inception of ideas to fully tested production items. Among the more important features are the power laboratory, the impulse and high-voltage labo-

Condensation of paper 59-60, recommended by the A I E E Protective Devices Committee and approved by the AIEE Technical Operations Department for presentation at the A I E E Winter General Meeting, New York, N.Y., Feb. 1-6, 1959 Published in A I E E Power Apparatus and Systems, Aug. 1959, pp. 489-98.

F. E . Andrews and Alex Vitkus are with Hubbard and Company, McCook, 111.

T h e authors wish to acknowledge the work of Dr. C. S. Sprague in the design, development, and construction ol the 3,000,000-volt and the 80-kilowatt-second high-current surge generators described in this article. These generators were originally built under his direction at Purdue University.1

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ratory, model shop, and indoor and outdoor mechanical laboratories. Fig. 1 shows an over-all view of the labo­ratory. Its general plan and size are shown in Fig. 2.

The 63- by 68-foot high bay portion of the laboratory building houses the high-voltage equipment and most of the other electrical test equipment not in the power laboratory. Its height, 57 feet to the roof trusses, was determined by the 24-foot clearance required from the top of the high-voltage surge generator.

POWER LABORATORY

T H E POWER LABORATORY is shown at the left of both Figs. 1 and 2. It duplicates power system operating voltage and current conditions, especially with respect to short-circuit testing of protective devices. The prin­cipal elements and connections are shown in Fig. 3.

Test energy supply is at 138 kv single phase line to line, from a short radial circuit originating at a major transmission substation of the local utility. High-capacity transmission lines from several principal gen­erating sources converge at this substation.

Transformation to test voltages is provided by a Class OA 2-winding transformer designed for an inter­mittent maximum short-circuit duty cycle of six 12-cycle tests per hour. Voltage rating is 138/18 kv through 1.5 kv in 1.5-kv increments, with each of the low voltages obtained through selective use of taps brought out through 10 roof bushings. Connections from these low-voltage bushings to the main test bus are completed through selector disconnect switches which can be closed in the proper combinations to provide the test voltages and capacities desired. The low-voltage wind­ing consists of two 9-kv sections which can be used singly or in parallel for voltages of 9 kv and less to obtain two ranges of capacity and impedance. The two sections in series provide voltages between 9 kv and 18 kv. The transformer is capable of delivering 254,000 kva asymmetrical, from an infinite bus.

Adjustments of test current, power factor, and re­covery voltage are accomplished in the circuit-adjust­ment bay, shown in Fig. 4, by connecting appropriate reactors, resistors, and capacitors into the circuit ahead of the test specimen. A number of transformers also are employed to obtain voltages and currents outside the range obtainable directly from the main trans­former. For this purpose, the following major trans­formers are being added to the power laboratory:

1. A series regulating transformer on the load side of the main transformer to provide voltage steps as low as 0.33 per cent above or below the main transformer output voltages.

Andrews, Vitkus—New Electrical Research Laboratory E L E C T R I C A L ENGINEERING

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E L E V A T I O N

F i g . 2 (Jef f ) . P l a n o f l a b o r a t o r y .

1-138-kv o i l circuit b r e a k e r 2 - M a i n test t rans former 3 - O v e r c u r r e n t pro tec t ion b a y 4 - l m p e d a n c e a n d t rans former b a y s fo r circuit ad jus tment 5 -Test b a y 6 - S a f e t y v i e w i n g r o o m 7 -Tes t cell 8—Initiating surge g e n e r a t o r 9 - H i g h - c u r r e n t surge g e n e r a t o r

1 0 - H i g h - v o l t a g e surge g e n e r a t o r Π - 6 0 0 - k v 60-cycle test set 1 2 - P o w e r l a b o r a t o r y cab le te rmina l 1 3 - D i s t r i b u t i o n - e q u i p m e n t life test structure 14-4-kv t rans former station 1 5 - C o n t r o l r o o m a n d master conso le 1 6 - P h o t o g r a p h i c l a b o r a t o r y 17 -Un ive rsa l mechan ica l testing machines 1 8 - M o d e l s h o p 19- lnsu la t ing mater ia ls l a b o r a t o r y 2 0 - A n a l y t i c a l l a b o r a t o r y 21-Of f ices a n d dra f t ing r o o m 2 2 - C o n f e r e n c e r o o m , l i b r a r y , a n d h i g h b a y l a b o r a t o r y o b ­

se rva t ion r o o m 2 3 - H i g h b a y l a b o r a t o r y 2 4 - W i r i n g trenches 2 5 - D - c ba t te ry r o o m

2. A high-current low-voltage transformer to provide short-time test currents as high as 200,000 amperes rms for 4 seconds.

3. An auto-transformer, 18/27-36 kv, to provide full power laboratory capacity at voltages between 18 and 36 kv.

The test specimen may be located in either the out­door barricaded test bay or the enclosed test cell shown in Fig. 5. The latter is a reinforced-concrete impact-resistant fireproof structure, suitable for testing oil-filled or other equipment for additional safety in case of an oil fire or flying parts. An overhead line extends beyond the test cell. This may be energized from the test bus, and is useful for testing varied construction

and equipment under actual line operating conditions. Primary overcurrent protection is provided by the

138-kv oil circuit breaker and its overcurrent induction relays. Power fuses or expulsion fuse cutouts, used ac­cording to duty required for the particular tests, pro­vide overcurrent protection for normal testing, with back-up protection by the low-voltage oil circuit breaker and its relays.

Power laboratory test operations for overcurrent pro­tective equipment tests are normally initiated by fir­ing a small surge generator to sparkover the initiating gap in the test circuit. For combined power and surge-current testing, as for lightning arresters, the test is initiated by applying the test surge directly to the test specimen. The tes: is precisely initiated at any selected

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U N D E R G R . C A B L E T O H I G H B A Y L A B .

F i g . 3 . P o w e r l a b o r a t o r y c o n n e c t i o n d i a g r a m .

D E C E M B E R 1959 Andrews, Vitkus—New Electrical Research Laboratory 1201

for discharge. A column of capacitors shunted by resis­tors, seen in front of the generator, assists in shaping the output wave, serves as a divider for voltage meas­urement, and provides tap-off points for test voltages intermediate between the three established output voltages.

The high-current surge generator, shown schemati­cally in Fig. 7, has maximum ratings of 80 kilowatt-seconds and 150,000 and 300,000 amperes crest at 100 kv and 50 kv, respectively. Practical output current crest with circuit constants adjusted to produce a standard 10x20-microsecond current wave at 100 kv is approximately 100,000 amperes. The connecting bus work and test specimen are located in the center to provide the lowest impedance.

Deflection pulses from the high-voltage and high-current surge generators are brought into the control room for instrumentation, by coaxial cables in copper-lined troughs.

The laboratory also has three other surge generators, all portable, for use either inside or outside in the power laboratory. Their voltage ratings are 500 kv, 250 kv, and 125 kv. Each can be operated either from an individual console at the site where located, or from the master control console. They can be used sepa­rately or combined and co-ordinated with the larger

F i g . 4 . I m p e d a n c e s e c t i o n o f c i r c u i t - a d j u s t m e n t b a y .

point on the 60-cycle voltage wave by a synchronously rotating device which triggers the surge generator. Rotating the synchronous motor frame adjusts the firing angle and produces a predetermined condition of short-circuit current asymmetry.

SURGE GENERATORS

T H E HIGH-VOLTAGE surge generator' shown in Fig. 6, has maximum ratings of 3,150 kv and 40 kilowatt-seconds. Taps divide the generator into sections to provide lower voltages. Practical maximum output voltage is 2,450 kv for the 1 i/2x40-microsecond wave for which the generator is normally arranged. Crest voltages of 950 kv and 350 kv are available from the tapped sections. The generator is comprised of 32 capacitors connected in the special Marx circuit shown in Fig. 7. Its distinctive feature is the elimination of interstage resistors usually used in the conventional Marx circuit. This provides more effective charging and reduces energy losses during discharge. It is made possible by mechanical switching of charge and dis­charge gaps and connections. The charging contacts and discharge gaps are mounted on four vertical shafts extending from bottom to top through the center of the generator. They are rotated between charge and dis­charge positions by a compressed air actuator to con­nect the capacitors in parallel for charge and in series

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F i g . 5 . E n c l o s e d test cel l a n d o u t d o o r test a r e a . S a f e t y v i e w i n g r o o m is a t r e a r o f test c e l l .

Andrews, Vitkus—New Electrical Research Laboratory E L E C T R I C A L ENGINEERING

F i g . 6 C f e r » . H i g h - v o l t a g e s u r g e g e n e r a t o r . F i g . 7 ( a b o v e ) . S i m p l i f i e d c i rcui t d i a g r a m o f m a i n s u r g e g e n e r a t o r s .

surge generators for investigation of multiple-surge phenomena and surge and power follow investigation. For such work, 60-cycle power is available inside through an underground cable connection from the power laboratory.

CONTROL AND INSTRUMENTATION

CONTROL AND INSTRUMENTATION tor the entire labo­ratory are centered in the master control console, in a room with windows overlooking the high bay labora­tory. Twelve main panels cover the full range of test operations. Fig. 8 shows the right-hand section of the main console. Each panel is equipped with meters and devices to implement the control and operating func­tion for which it is intended and to give readings of all electrical or other relationships applicable to that func­tion.

The two power laboratory panels include the usual oil circuit breaker controls, voltmeters, and ammeters. They also have mimic busses and solenoid-operated mimic switches to represent disconnect switches. A dial switch associated with a system of indicating lights and operating mechanism interlocks assures correct opera­tion of the test transformer voltage-selector disconnects. Certain of the disconnect switches have photoelectric relays operated from targets on the switchblades to indicate, at the console panel, the switch position.

T o provide personnel safety, the power laboratory test initiation circuit is completed through interlocks on the yard gates and finally through a foot switch in

D E C E M B E R 1 9 5 9

the test area viewing room. This permits the test moni­tor to stop a test if the power laboratory yard is not clear of personnel or if other questionable conditions develop. A reversible loudspeaker-microphone arrange­ment provides continuous communication between the control console operator, the yard area, and the test viewing room.

F i g . 8 . M a s t e r c o n t r o l c o n s o l e , r i g h t - h a n d s e c t i o n . O s c i l l o g r a p h c o n ­s o l e is a t r i g h t .

Console panels are provided for each of the several surge generators and the two 60-cycle high-voltage test sets. A wet-fiashover test panel monitors water precipi­tation rate, conductivity, and pressures.

The console provides complete automatic timing and sequencing of test operations for both power and surge laboratories. This includes charging and triggering of surge generators, starting and stopping of oscillographs and motion-picture cameras and test initiation. A sequence may be started by push button control or it may be set up for automatic repetitive starting.

1203 Andrews, Vitkus—New Electrical Research Laboratory

OSCILLOGRAPHY

A CATHODE-RAY OSCILLOGRAPH is provided for observ­ing and recording surge and other transient phenom­ena. Its portable console, with control equipment and instruments, is normally used inside a metal mesh enclosure electrically shielded and isolated from other equipment except for a single ground connection com­mon with the surge generator in use. Power for the oscillograph is supplied from a single-phase 120-volt a-c generator inside the cage, driven by an insulated shaft coupled to a motor outside.

Both pen writing and photographically recording magnetic oscillographs are used for power system re­cording. They can be located either at the test site, in the control room, or in the photographic laboratory. Their operations may be controlled automatically either from the master console or from one of the portable consoles.

PHOTOGRAPHY

PHOTOGRAPHY is an important tool of the laboratory for both analytical and record work. Ultrahigh-speed motion-picture photography is used extensively. For this, a rotating-prism camera with speeds up to 8,000 frames per second is employed. T o provide adequate lighting for the short exposure associated with such high speed, a recently developed high-intensity xenon quartz bulb lamp is used. The camera and lamp have a co-ordinated timing control tied in with the control console so that their operations are properly timed and integrated with the entire test operation.

Conventional still and motion-picture cameras are used widely. A photographic laboratory is provided for on the job processing and for general photofinishing.

With these facilities, it is possible to carry on prac­tically any type of photography and to reduce to slow motion such extremely fast movement as occurs with circuit breaker or fuse cutout mechanisms subjected to forces associated with electric arc extinction.

O T H E R FACILITIES

A NUMBER OF OTHER FACILITIES round out ability of

the laboratory to conduct the wide variety of work required for development, engineering, and testing of products for power and communication utilities. Instal­lation of some of these is still in progress. Among the more important of such facilities are the following:

1. Power-frequency high-voltage test sets with maxi­mum voltages of 600 kv and 100 kv.

2. Portable consoles for control and instrumentation at the test site.

3. Wet-flashover test equipment, 4. Heat-run test equipment, complete with current

supply, portable console, and automatic temperature recorder, to provide continuous currents up to a maxi­mum of 40,000 amperes.

5. Insulating materials laboratory. 6. Analytical laboratory for physical and chemical

testing.

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F i g . 9 . U n i v e r s a l t e s t i n g m a c h i n e . D e f l e c t o m e t e r is a t le f t a n d g r a p h i c r e c o r d e r a t r i g h t .

7. Mechanical laboratory with universal testing ma­chines, equipped with load-deflection graphic recorders, as shown in Fig. 9.

8. Outdoor mechanical test installation for full-scale testing of line hardware and structures.

REFERENCE

1. Design of a Three Million Volt Impulse Generator, N. W. Richards. Λί. S. Thesis. Purdue Universirv Lafayette, Ind., June 1950.

Giant "Four-Leaf Clover"

Appearing as a giant four-leaf clover is one of the two propellers that will drive the cruiser U. S. 5. Long Beach, the Navy's first atomic-powered surface ship. The two reactor plants were designed and developed by Westinghouse Electric Corporation for the Naval Reactors Branch, U. S, Atomic Energy Commission. Bethlehem Shipbuilding Division of Bethlehem Steel Company is the designer and builder of the guided-missile cruiser, which is 721 feet long.

Andrews, Vitkus—New Electrical Research Laboratory E L E C T R I C A L ENGINEERING