Abstract:
An electrical parameter analyzer analyzes samples of electrical power by executing program instructions stored on a PCMCIA compatible program card. The analyzer has a central processing unit including a microprocessor which reads the program card and passes program instructions to an acquisition control processor and an input/output controller, each of which has its own microprocessor. A series of values for a characteristic parameter of the electrical power are generated by the acquisition control processor, and these values are printed under control of the input/output controller upon request of the central processing unit.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to apparatus for analyzing the performance of electrical power supply systems. Examples of prior art analysis devices are disclosed in Talambiras, U.S. Pat. No. 4,414,638 and in McEachern et al., U.S. Pat. No. 4,642,563. A typical commercially available device is the Dranetz 8000-2 Energy Analyzer, sold by the assignee of the present application. 
     The Dranetz 8000-2 and other prior art devices have contained hardware and firmware tailored for specific applications. Thus it has been necessary to purchase one instrument for generation of power quality data and a second instrument for generating power consumption data. Yet a third instrument was required for motor inrush analysis. 
     Prior art electrical parameter analyzers have used microprocessors for analyzing energy measurement signals provided by suitably configured probes and in some cases have employed memory cards for recording the results in machine readable form. This has enabled them to perform sophisticated power analyses and to store a series of resulting parameters in an efficient and informative manner. However, the single-purpose design of such prior art electrical parameter analyzers has imposed serious economic and operational constraints. Thus there is a need for an improved electrical parameter analyzer which is essentially unlimited in its ability to handle widely divergent energy analysis functions. 
     SUMMARY OF THE INVENTION 
     This invention provides an electrical parameter analyzer equipped with means for reading a program card upon which are recorded programming instructions for directing the operation of one or more microprocessors mounted within the analyzer. The program card contains all programming instructions for analyzing a series of parameters characterizing an electrical power supply. It is a feature of this invention that the electrical parameter analyzer is initialized by a &#34;boot&#34; file which is stored in ROM. This file enables the microprocessor to read the program card, perform diagnostics and execute a series of recorded instructions. Without a program card the electrical parameter analyzer is merely a limited capability three-phase watt meter. However, when the instrument is turned on with a program card in place, it is capable of conducting electrical parameter analyses which are limited only by the power of the microprocessor, the imagination of the programmer who programmed the program card and the physical characteristics of the measuring circuitry. 
     Preferably the present invention utilizes a program card which complies with Personal Computer Memory Card International Association (PCMCIA) standards and has an attribute memory section which is logically and physically separate from the common memory. Program control code for the electrical parameter analyzer is stored in the common memory, while information identifying the hardware and the task to be performed is stored in the attribute memory section. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a right, front perspective drawing of an electrical parameter analyzer. 
     FIG. 2 is a rear view of a control module for the electrical parameter analyzer of FIG. 1. 
     FIGS. 3A-3F are a block diagram of electronic components for the electrical parameter analyzer. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The electrical parameter analyzer of the present invention may be packaged in a manner quite similar to the Dranetz 8000-2 energy analyzer. Thus, as illustrated in FIG. 1, the electrical parameter analyzer 10 may comprise a display/keyboard module 14 mounted on a control module 13 which in turn is supported by a cradle-type stand 12. It may be provided with a graphics printer 16 comprising a roll of thermally sensitive paper, a thermal printhead, and an appropriate paper take-up motor. 
     Electrical parameter analyzer 10 also has a liquid crystal display (LCD) 18 for real time display of electrical signals. Data collected by electrical parameter analyzer 10 may be recorded upon a static RAM data card 22 received within a card slot 20. Data card 22 preferably has a 68 pin connector and complies with PCMCIA standards. Data card slot 20 is equipped with a compatible 68 pin receptacle. Electrical parameter analyzer 10 also has a series of function keys 24 and a numeric keypad 26. 
     Referring now to FIG. 2, the input/output connections for the electrical parameter analyzer 10 will be described. Thus, the electrical parameter analyzer may have four positive voltage input terminals 28, four negative voltage terminals 29 and a ground connection terminal 31. Alongside voltage input terminals 28 are four current probe connectors 30. This enables simultaneous monitoring of voltage and current in four analog channels. A digital input connector 32 enables reception of four channels of digital information. There is also a conventional parallel port 34 and a 25 pin RS-232 D serial port 36 for 300-9600 baud communications. Serial port 36 may be connected to a suitable internal or external modem. An optional internal 2400 baud FAX/modem can be accessed via RJIIC jack 27. 
     A key feature of the invention is program card slot 38 which receives a PCMCIA compatible 68 pin program card 40. Program card 40 contains a solid state common memory and a physically separate solid state attribute memory. The common memory contains program control code for controlling three internal microprocessors 212, 300, 400 (illustrated schematically in FIGS. 3C, 3D and 3E) to analyze electrical signals received via the above-described connectors. The attribute memory contains information such as program card identification, options, purchase date, program card version and general information about the program code stored in the common memory. By way of example, the program code on program card 40 may instruct the internal microprocessors to accept digital inputs from the keypad, interpret those inputs as start/stop intervals for monitoring and recording current and voltage on four input channels, displaying the signals on LCD 18, creating a graphic record thereof on graphics display 16 and creating a machine-readable record thereof on data card 22. A different card may contain program code for analyzing harmonic distortion of voltage, current and power on four input channels and recording the results both graphically and in a text format. 
     As hereinafter described with reference to FIGS. 3A-3F, each of the microprocessors has an associated ROM containing a stored boot routine. These ROMs initialize the microprocessors and enable them to read the program code on program card 40. All functionality and features of the instrument are in the program card code. 
     Electrical parameter analyzer 10 has four major subsystems as generally illustrated in block diagram form in FIGS. 3A-3F. They are the data acquisition subsystem 42 (shown partly in FIG. 3A and partly in FIG. 3B), an acquisition control processor (ACP) 44 (FIG. 3C), an I/O controller 46 (FIG. 3D) and a central processing unit 50 (FIG. 3E). An external memory card controller 442, a contrast control board 54, an LCD panel 56 and a keypad board 58 (all illustrated in FIG. 3F) are connected to central processing unit 50. There is also a power supply (not illustrated). Microprocessors 212, 300 and 400 are incorporated within ACP 44, I/O controller 46, and central processing unit 50 respectively. In the preferred embodiment described herein all three microprocessors are supplied by Motorola. Microprocessors 212 and 400 are sold under the designation MC68EC020 while microprocessor 300 is sold under the designation MC68HC11. 
     Referring now to FIG. 3A, data acquisition subsystem 42 is connected for receiving inputs from the various terminal devices illustrated in FIG. 2. Positive and negative inputs from a current probe connector 30 are supplied to a differential amplifier 126. It will be appreciated that there are four such differential amplifiers 126, only one of which is illustrated. Positive voltage inputs are supplied to three attenuators 106 (only one being illustrated), and a fourth attenuator 107. Negative voltage inputs are supplied to three attenuators 108 (only one being illustrated), as well as to a fourth attenuator 109. A range select circuit 111 is connected between attenuator 107 and its associated attenuator 109. Output signals from attenuator pairs 106,108 are applied to three corresponding differential amplifiers 112 (again, only one being illustrated). The output from each differential amplifier 112 is supplied to a corresponding low pass filter 114 and to a pair of corresponding peak detectors 152,154 via an associated one of three lines 990. Output signals from voltage attenuators 107,109 are similarly applied to a differential amplifier 113 which is connected to a low pass filter 115 and to a pair of peak detectors (not illustrated) identical to peak detectors 152,154 via a line 989. Correspondingly, the output from each differential amplifier 126 is supplied to a low pass filter 124 and to a pair of peak detectors 156,158 via an associated line 988. 
     Output signals from low pass filters 114,115 and 124 are applied to corresponding sample and hold circuits 120,122,123 respectively which in turn are connected via lines 991b, 991d and 991e to a multiplexer 118 (FIG. 3B). This provides for simultaneous sampling of all eight input channels. The output signals from low pass filters 114,115 are also applied via a line 991a,991c to a multiplexer 116 (FIG. 3B) which supplies inputs to a zero crossing detector 128. Voltage and current samples from multiplexer 118 are applied to a range detector 140 and to a variable gain amplifier 142. To summarize, the voltage and current inputs break off and travel in parallel for low frequency sampling as required for power quantity type measurements. 
     High frequency processing is accomplished by a pair of multiplexers 160,162 and four sample and hold circuits 164, 166, 168 and 170 connected via lines 901-904 to a multiplexer 172. Multiplexer 160 is supplied with inputs from peak detectors 152,154 as well as from similar pairs of peak detectors serving the other above described voltage channels. The four sets of current peak detectors 156,158 are connected to the input side of multiplexer 162. High frequency samples from multiplexer 172 are applied to an A/D converter 174 and thence to a FIFO 150 for application to ACP 44 via a mother board as illustrated schematically by line 993. 
     Amplified voltage and current signals from variable gain amplifier 142 are applied to an analog-to-digital converter 144 and then are processed by a FIFO 146 for transmission to the ACP 44 by line 993. A probe serial data link 148 also may supply data to ACP 44, again through the mother board. The output from zero crossing detector 128 is applied to a multiplexer 130 for transmission to a phase locked loop 132 which is connected to an acquisition control logic circuit 138. Acquisition control logic 138 provides synchronizing signals for multiplexers 118, 172 and A/D converters 144,174. 
     Phase locked loop 132 may be manually controlled by keyboard commands applied via a bus line 992 to DAC 134. A V/F circuit 136 receives the manual control signals in analog form from DAC 134, converts them to frequency adjustments and routes them to the phase locked loop via multiplexer 130. 
     The main purpose of ACP 44 is to acquire data in real time from data acquisition subsystem 42, process that data, perform calculations thereon, and transfer the results through the mother board via line 993 to the central processing unit 50. The memory section of ACP 44 comprises a boot ROM 202, a data RAM 204, a program RAM 206, and an EEPROM 208. EEPROM 208 stores calibration information for use by the data acquisition subsystem 42. 
     When electrical parameter analyzer 10 is turned on boot ROM 202 boots microprocessor 212 and passes control to CPU 50. Then, if so instructed by CPU 50, program control instructions for microprocessor 212 are read from CPU 50 and loaded into program RAM 206. Microprocessor 212 then comes under execution control of program RAM 206. If program card 40 is not installed in program card slot 38 at the time of startup, then electrical parameter analyzer 10 operates as a simple three-phase watt meter using a set of minimum logic instructions stored within boot ROM 202. 
     ACP 44 has a bus 83 which connects ROM 202, RAM 204, RAM 206, EEPROM 208 and microprocessor 212 to a watchdog reset circuit 210, a control signal generation circuit 214, a DUART 220, a relay control 224, an A/D converter 228, a digital input interface 234, frequency counters 244, a databus interface 246, a FIFO status interface 248 and a dual port interface 260. DUART 220 is serviced by a 3.6864 MHz crystal oscillator 221 and by serial port 223. An oscillator 225 generates clock signals for microprocessor 212. 
     A clock circuit 240 generates 1 MHz, 64 KHz and 1 KHz clocks by counting clock pulses supplied by a 4 MHz oscillator 242. A transducer input block 232 supplies transducer signals to an analog multiplexer 230, which is connected to the input side of the A/D converter 228. Four channels of digital input signals may be applied to terminal block 32 for transfer to an optical isolation circuit 236 which is connected to digital input interface 234. Dual port interface 260 is connected through the mother board via line 994 to a dual port RAM 430 (FIG. 3E) in central processing unit 50. 
     Referring now to FIG. 3D, I/O controller 46 has a boot ROM 310 which communicates with microprocessor 300. Boot ROM 310 operates in a manner similar to boot ROM 202 in that it initializes microprocessor 300 at startup. Following startup, microprocessor 300 loads program instructions from CPU 50 into a program RAM 306. These instructions are used by microprocessor to control the operations of printer 48. A dual port interface 314 is connected via a line 995 through the mother board to a dual port RAM 424 in CPU 50. Reading of program card 40 is under control of central processing unit 50 which routes appropriate program code to ACP 44 and I/O controller 46 via the mother board and dual port RAMs 424,430 respectively. A bus 301 within I/O controller 46 interconnects microprocessor 300 with ROM 310, program RAM 306, a temporary storage RAM 312, a parallel port 34, a DUART 316 and a printer controller 328. 
     Printer controller 328 controls printer 48 which in turn comprises a paper takeup motor 340 and a 320 dots-per-line thermal printer 341. A burn timer 326 is connected to printer controller 328 for controlling the operation of thermal printer 330. DUART 316 receives input signals from RS232 port 320 and an optional modem/fax 318. DUART 316 operates under control of a 3.6864 MHz crystal 324. CPU 300 operates under timing control of a 12 MHz crystal 322 and is provided with inputs from a watchdog/reset circuit 302 and a voltage monitor 304. 
     As illustrated in FIG. 3E, central processing unit 50 has its own boot ROM 402 and program RAM 404 interconnected by a data and address bus 421. These units operate in a manner similar to the above-described boot ROM and program RAM units of ACP 44 and I/O controller 46 so as to control the operation of microprocessor 400. Central processing unit 50 also includes dual port RAMs 424, 430 which are mentioned above, as well as a non-volatile RAM 406 and a system RAM 410. A lithium battery 408 powers non-volatile RAM 406. 
     Other elements of central processing unit 50 include a watchdog/reset circuit 434, a 16 MHz clock 436, a general I/O circuit 426, an audible alarm 428, a time keeper alarm 429.and a control signal generator 414. An LCD interface 418 controls LCD frame memory 416 which in turn services LCD panel 56 (FIG. 3F) via a line 998. A keypad interface 412 communicates with keypad board 58 via a line 997. 
     A program card interface 420 connects program card 40, received in program card slot 38 to bus 421 via a line 923. Control signal generator 414 operates under control of microprocessor 400 for selectively causing program card interface 420 to address either common memory 498 or attribute memory 499 of program card 40. External memory card interface 432 connects bus 421 to an external memory card controller 422 through a bus 996. External memory card controller 422 accesses digitized data stored on data card 22, received in data card slot 20. 
     While the method herein described, and the form of apparatus for carrying this method into effect, constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the invention, which is defined in the appended claims.