Westinghouse Electric Co. (1886-1990)

Shallenberger Ampere-hour Meter (Single Phase)

(1888 to 1897)
This was the first successful AC ampere-hour meter developed by Oliver B. Shallenberger, Westinghouse's chief electrician. In 1888, he and an assistant were working on a new AC arc lamp one day and a spring fell out, landing on a ledge inside the lamp. The assistant went to replace the spring, but Mr. Shallenberger noticed the spring was rotating slowly due to fields within the lamp and told the assistant to wait until they figured out why the spring was rotating. After some investigation, Mr. Shallenberger declared that he could come up with a meter based on the principle of that rotating spring, and after only three weeks of rapid-fire experimenting, he had a working design ready for market. This meter paved the way for acceptance of the more efficient AC distribution system over DC. This meter had one disadvantage - it measured all the current flowing through the circuit regardless of the load which made it unsuitable for use with motors, because there was no voltage element to take power factor into account. The motor inside this meter was not much different from the shaded-pole AC motors commonly used today. In order to keep the meter's speed proportional to the amperes, this meter used a fan assembly for the brake. Unlike other meters of its day, this meter fastened to the wall by means of the two wooden straps on the back. 
Photo: Charles Crider collection

Shallenberger Integrating Wattmeter (Single Phase)

(1894 to 1897)
By the mid-1890s, Shallenberger's ampere-hour meter was popular but because of the increasing use of motors, a true watthour meter was needed to account for varying voltages and power factors. Shallenberger rose to the challenge and came up with a new meter which was the first commercially produced induction watthour meter. It was large, heavy (41 pounds!), and more than twice as expensive as comparable meters in its time. This meter was one of the first models to use a cyclometer register. Depending on the customer's preference, this register was equipped with 4 drums (registering in kwh) or 7 drums (registering in watthours). The stator was similar to ones in later meters with its voltage and current coils arranged on opposite sides of the disk and had a magnet assembly to damp the disk's speed.
Photo: Westinghouse Handbook on Watthour Meters

Shallenberger Integrating Wattmeter (Polyphase)

After coming out with his single phase watthour meter in 1894, O.B. Shallenberger designed a polyphase version. It was just as big and heavy as his single phase meter (40+ pounds). However, the stators were too close to each other and interfered with each other with a resulting loss of accuracy. 
Photo: GE Polyphase Metering Course Pamphlet

Round Type (Single Phase)

(1897 to 1903)
The Shallenberger 'integrating wattmeter' met the industry need for a watthour meter, but it was too heavy and expensive. Since O.B. Shallenberger was too ill at the time to do any further work, two other engineers (H. P. Davis and Frank Conrad) were selected to design a lightweight and cheap watthour meter, and their result was known as the 'Round Type' or Davis & Conrad meter. This meter was much lighter at only 12 pounds, and introduced several features that are still in use today on modern meters: lightweight disk, small air gaps, power factor adjustment, and separate covers for the movement and terminals. This meter is quite distinctive with its 5-dial watthour register and terminal chamber located on the back of this meter. The light load adjustment on this model was unique as it involved varying the voltage supplied to the voltage coils. The Round Type meter was the last model made by Westinghouse to use a pivot-type bearing. There are 2 types of nameplates known on the glass-covered Round Type meters - a large porcelain-faced plate and a smaller brass plate.
Electrical Meterman's Handbook

Round Type (Polyphase) 

After Shallenberger's and Thomson's (GE) attempts at a workable polyphase meter, an engineer at Westinghouse (Paul McGahan) devised this polyphase meter which was simply two single phase Round Type meters in a tall case with a common shaft and register. The terminals for this meter were on the back, at the top and bottom.
Photo: Westinghouse Handbook on Watthour Meters 

Type A (Single Phase)

(1903 to 1904)
This meter was identical to the Round Type except for two major changes. One was to relocate the terminal chamber from the rear to a more accessible position on top. The other was to introduce a new bearing which consisted of a steel ball rotating between 2 jewels, and which would eventually displace the pivot-type bearing as the industry standard (superseded only by the magnetic bearing brought out by GE in 1948). Most Type A meters in existence have cast metal covers but some were produced with glass covers. A three-wire version of the Type A was also made, and this version is the only AC meter that is physically different from its two-wire version.
Photo: Westinghouse Handbook on Watthour Meters

Type A (Polyphase)

The Type A polyphase is identical in appearance and design to the Round Type polyphase meter. The only difference is that the Type A polyphase meter has a ball-type bearing.
Photo: Westinghosue Handbook on Watthour Meters 

Type A (Switchboard)

(1903 to 1906)
The Type A switchboard meter was available in both single phase and polyphase versions, and both were identical to the service type except for having a cover with a flange for mounting into an opening in the switchboard. 

Type B (Single Phase)

(1904 to 1906)
This meter was a complete redesign from the previous Round Type and Type A meters. The most important change was a redesigned stator that eliminated the reactance coil from the voltage circuit. This new design also allowed more room for the current coil, allowing heavier wire to be used which in turn increased its overload capacity. The new stator design also made it possible to use a separate frame to support all the internal components instead of bolting everything to the base. The register also got 2 important changes - one was rearrange the dials into a straight line (dropping the fastest dial and therefore registering in kilowatthours) for ease in reading. The other was partly because of the introduction of the internal frame - the upper end of the disk and the register were now supported separately instead of as an unit, making maintenance easier. The disk assembly is also larger (possibly due to higher torque of the new stator with its basic constant of 1/3 instead of 1/6) and is embossed with an arrow pattern for rigidity. In addition to redesigning the case to eliminate provisions for the reactance coil and simplifying the support for internal components, the terminal chamber was also improved. Besides changing to 4-terminal construction, the terminals were now supported with bushings on one end and a piece of insulating board on the other so damaged terminals could be replaced individually (the Round's and A's terminal chamber have the terminals cast into place with cement). This model can easily be told apart from the more easily found (but still scarce) Type C by the fact the metal cover is cast and that screws are used to fasten the covers to the base.
Photo: Westinghouse Handbook on Watthour Meters

Type B, Early Version (Prepayment)

(1904 to 1906)
This version of the Type B prepayment meter has much in common with the Type B single phase meter, such as tailed pointers, screws for the covers, and the meter is labelled 'watt meter'. The coin slot is a simple chute with the opening out of the way of the incoming line wires. On both versions, the large dial on this meter shows the number of quarters to the customer's credit. The service was connected and disconnected by means of a solenoid that was operated by a differential gear on the meter register.
Photo: Westinghouse Handbook on Watthour Meters 

Type B, Later Version (Prepayment)

(1906 to 1910)
This resembles the early version, except many of the changes that occurred in the transition from the Type B to the Type C show up in this meter also. (Why didn't they call it the Type C prepayment meter?) The dials are plainer, wing nuts are now used for fastening the covers, and most importantly, the meter is now labelled as 'watthour meter'. The coin slot entrance was redesigned for this version but unfortunately it would have been right behind one of the incoming wires.
Photo: Unknown collection

Type DC, Plain & Sub A (DC)

(1906 to 1912)
Westinghouse was the last company to enter the market for DC meters and may only have done so to remain competitive. The first version of their Type DC (Direct Current) meter was similar in design to what GE and Duncan were building, except that the internal components were much closer together. The second version of the type DC meter (Sub A) was a different design with the brake magnets on top and a window for the disk. There is also an earlier version of the DC that was produced in a case similar to the early polyphase Type C meter, but I have no further info at this time.
Photo: Westinghouse Handbook on Watthour Meters

Type C (Single Phase)

(1906 to 1911)
This meter had two major versions: In the early Type C, a stamped steel base was used and the terminal chamber used on the Type B was replaced with a porcelain terminal chamber recessed into the top of the main body of the meter. There are two variations of this style, the terminal covers using either screws or wing nuts. This arrangement was apparently inconvenient as Westinghouse soon reverted to the basic design of the Type B and continued with little change until the introduction of the OA meter. There are several variations of this second style, and they are shown below. The two in the middle are the most commonly found versions, but even these two styles are fairly scarce.
Photo: Westinghouse Handbook on Watthour Meters

Type C (Polyphase)

(1906 to 1915)
As with the single phase version, there are two major versions of the polyphase Type C. The first version has recessed porcelain terminal blocks in the sides of the meter. The later version is wider and has a terminal compartment on either side of the meters. However, unlike the later OA polyphase meter, the wires enter at the TOP and BOTTOM of each terminal block.
Photo: Electrical Meterman's Handbook

Type C (Switchboard)

(1906 to 1911)
This model came in two versions: a round metal case with binding posts around the edge or a glass rectangular back-connected version. Both versions were available in single phase and polyphase styles. The register is a 5-dial version with the large hand being the fastest dial for use where daily readings were taken of power delivered.
Photo: Westinghouse Handbook on Watthour Meters

Type CW-6 (DC)

(1912 to 1920s)
The Westinghouse CW-6 meter was a clone of GE's C-6 DC meter, and they may have obtained licenses to manufacture this meter through the Board of Patent Control (which was dissolved in 1911) they shared with GE.
Photo: Westinghouse Handbook on Watthour Meters

Type OA (Single Phase)

(1910 to 1928)
The earliest OA meters were simply an improved version of the previous Type C meters and are of almost identical construction (see first picture). The first picture is of the top-connected style, and also shows the first-generation (embossed) metal cover used on the OA meter (Bottom-connected OAs also exist with this cover). The top-connected style was soon discontinued in favor of the bottom-connected style, and the next major change was to consolidate the meter data onto one nameplate (earlier OA meters have a nameplate on the base as well as capacity markings on the register). Most of the OAs in existence will have this plain metal cover with a small nameplate on front. The final major change was a redesign of the internal frame for better access to the internal connections. Most bottom-connected OA meters are wired with the line terminals on the left side, but some earlier ones exist with the line terminals on the right side (some OAs also have blank terminal covers). A few high-capacity OA meters exist and have a smaller terminal box and cable terminals.
Photo: Westinghouse Handbook on Watthour Meters

Type OA (Polyphase)

(1915 to 1928)
The polyphase OA resembles the later Type C polyphase except for being smaller and having the terminals at the outer ends of the terminal blocks.
Photo: Westinghouse Handbook on Watthour Meters

Type OA (Switchboard)

(1910 to 1928)
The OA switchboard meter was a back-connected version of the standard single phase or polyphase OA meter. Disconnect and bypass links were provided within the meter for testing.
Photo: Westinghouse Handbook on Watthour Meters

Type OA (Prepayment)

(1910 to 1928)
The first OA prepayment meter superseded both versions of the Type B prepayment meter. The coins were inserted at the top of the meter and accepted by operating the lever at the top of the meter. The mechanism for operating the switch was spring-loaded and wound up as the lever was operated. The round window at the top showed the number of the quarters to the user's credit. Later on, this meter was replaced by a prepayment attachment that could be fitted onto a standard OA watthour meter (right picture). This was a condensed version of the prepayment mechanism used on the earlier OA prepayment meter, except that a credit dial is used instead of the standard kilowatthour register. If desired, a set of dials could be fitted to the mechanism that were visible through the disk window showing kilowatthours used by the customer. The prepayment attachment was operated by simply turning the knob as the quarters were inserted into the coin chute.
Photo: Westinghouse Handbook on Watthour Meters

Type OB (Single Phase)

(1924 to 1934)
In 1924, Westinghouse came out with the OB which was a radical departure from the OA's design. This meter was much smaller than the OA (and present-day meters) and in order to accomplish the size reduction, a special stator was used with both the voltage and current coils mounted above the disk. Unlike the OA's cast iron base, the base of the OB is of punched steel. Just like the Type C and OA meters, there are several styles of OB meters. The first picture is of the original version of the OB with metal cover and small nameplate. The second picture is of an OB with the original base and the 2nd generation nameplate. With S/N 9,000,000 Westinghouse changed the base (see third picture), possibly to make it fit better to meter service cabinets coming into use at that time. The fourth picture is of a high-capacity OB (25A, 50A, and 75A ratings). Over the next few years, various improvements were added to the OB's design to compensate for temperature and load variations. The last picture is of the FIRST socket-type meter, the OB 'detachable'. Note the rear view of the meter and the socket used with this meter.
Photo: David Turner collection

Type OB (Polyphase)

(1924 to 1941)
This series of polyphase meter was based on the OB single phase meter and were made in various 2-stator and 3-stator configurations for the polyphase circuits in use at the time. The meter shown was developed for use on 3-wire network circuits (like GE's I-18), and the polyphase version has a terminal chamber wider than the rest of the base.
Photo by Bud Russell

Type OB (Switchboard)

(1934 to 1946)
As with the OA, the OB switchboard meter was available in single phase and polyphase versions. However, there were no internal test links and an external test switch was required.
Photo: Westinghouse Handbook on Watthour Meters

Type OC (Single Phase)

(1932 to 1941)
In 1932, the OB meter was redesigned and released as the Type OC. The case is deeper than the OB, the cover now attaches to the base with a pair of bayonet studs, and an unique interlock allowed the OC to be secured with only one seal. The OC also incorporated all the improvements that Westinghouse phased in during the OB's production span which allowed better operation over a wider range of temperatures and loads. The very first OC meters started out with a 8-digit S/N in the 12 million range, then was quickly changed over to an alphanumeric serial number (1 to 5 digits with a letter at the end). This serial number scheme must have been a difficult one for the utilities to understand as numbering reverted to an 8-digit number in 1937. Some of the very last OCs made do have the same copper-plated brake magnets (the silver ones) as used on the CS and CA. Unlike the Type C, OA, and OB meters, the OC came in only 2 major styles: the normal bottom-connected version and a 'detachable' (socket) version. Although the CS and CA were introduced in 1934, the OC was manufactured in smaller quantities until it was dropped in 1941.
Photo: David Dahle collection 

C Series (Polyphase)

(1932 to 1941)
The C-2 through C-10 were the first Westinghouse polyphase meters to have a style number for each configuration (C-2: 3-phase 3-wire, C-3: 3-phase 4-wire Y 3-stator, C-4: totalizing, C-5: 3-wire network, C-6: totalizing, C-7: 3-phase 4-wire delta 2 stator, C-8: 3-phase 4 wire Y 2 1/2 stator, C-9: 3-phase 4-wire delta 3 stator, and C-10: 2-phase 5-wire). The stators were the same as used in the OC singlephase meter.
Photo: Westinghouse Handbook on Watthour Meters

Types JS & JA (Single Phase)

(1940 to 1954)
In 1940, the HFS and HFA meter were replaced by the JS and JA meters. The basic concepts behind the HFS and HFA meters were retained and updated. Initially, these meters were to be produced with chrome steel magnets, but just prior to production, these magnet assemblies were replaced with new Alnico magnets. The steel base on the HFS (which was prone to rusting out) was replaced with an aluminum base on the JS.
Photo: Pete Mallet collection

Types CS & CA (Single Phase)

(1933 to 1957)
The CS was a completely new design and the first of the modern socket meters. When meter mounting arrangements were standardized in 1934, the CS's enclosure design was emulated by the other manufacturers. The CA was introduced the same year when a new standard enclosure was developed for the bottom-connected single phase meters. The first CS and CA meters had the same alphanumeric serial number system as the previous OC meters (and use the same stator design). The magnet assembly on this group of meters were painted black as was done on the OB and OC meters. In 1937, these meters had two changes: The magnet assembly was now painted silver and the alphanumeric serial number format was abandoned, the first new serial number being #15,000,000. Starting in 1940 (#16,500,000) the magnet assembly got a heavy layer of copper plating for surge protection (but this method was not as effective as using Alnico magnets). During WWII, a limited number of meters were made and these have thin plated COPPER disks. Some CS and CA meters are known with cyclometer or odometer registers and these are not as common as the pointer-type register.
Photo by David Dahle

CS/CA Series (Polyphase)

(1937 to 1960s)
With the introduction of the standardized polyphase meter mountings, the C series polyphase meters were replaced by the CS and CA series polyphase meters. In order to meet the demand for a socket polyphase meter, Westinghouse reverted to using OB-style stators in order to squeeze the two-stator C series meters into the socket enclosure. The CS-3 three-stator socket meter uses an oval cover and an adapter base (similar to the Duncan MH 3-stator meters). The CA line of polyphase meters continued to use the same stators as in the C line of meters. In 1961, Westinghouse introduced an Alnico magnet that replaced the copper-plated chrome steel magnet that had been used since the late 1930s (shown on the 3-stator meter).
Photo: Joe Maurath Jr. collection

CB Series (Switchboard)

(1946 to 1963)
The CB series had two major changes over previous switchboard meters. First, since the CS/CA meter element was used, the meter was much more compact than earlier models. Second, a semi-flush mount version with built-in test switch was introduced as an option ("Flexitest" case) and these types have an F at the end of the model number. Later CB series meters have an Alnico magnet assembly instead of the copper-plated steel magnets.
Photo: Don Price collection

Types DS & DA (Single Phase)

(1954 to 1960)
In the 1950's, with metering technology improving, Westinghouse introduced a completely new design in their new DS and DA meters. Some of the major changes include: better overload compensation, larger register, Alnico retarding magnets cast into the frame (instead of the previous chrome steel magnet assembly), new stator design with adjustments in more accessible locations, and a compression-molded base. A new cover design was introduced with an anodized steel flange that was used in conjunction with a special sealing clip, but this did not last long as the industry preferred a more secure sealing solution. The current coils in the DS and DA were embedded in a polyester compound which unfortunately did not stand up well to the elements (the compound tended to crack as well as react with the copper in the coils). An all-metal cyclometer register (these have 4 vertical drums) was used on some of these meters but these developed problems with corrosion and fading and were replaced with a newer version that uses 5 horizontal plastic drums.

Photo: Pete Mallet collection

DSP & DAP Series (Polyphase)

(1954 to 1960)
The DSP and DAP series meters was a complete redesign of the older CS and CA series polyphase meters. The 9 polyphase styles introduced with the C line were narrowed down to 5 (the -4, -6, -9, and -10 were dropped). This series of meters has an unusual frame design consisting of 2 sections, the front section having one retarding magnet and supports the disk and register. The rear frame has the other retarding magnet and attaches to the base. The stators are supported by the rear frame and in turn support the front frame. The current coils were embedded in polyester and since they were much more exposed (particularly on the DSP - the DAP meters typically were inside or in enclosures) than in the single phase versions, the insulation was more prone to cracking and melting, hastening the elimination of this model from the field.
Photo: Lineman's Handbook