Equipment information

Clark Hess Communication Research Corp 255 Digital multimeter
Manufacturer:
Model:
255
Date:
1983
Category:
Group:
Description:
VOLT-AMPERE-WATT METER

Information

The Model 255 digital V-A-W meter provides TRUE RMS measurements of VOLTAGE, CURRENT, and POWER. These measurements are essentially independent of the waveshape and of the power factor from DC up to frequencies of hundreds of kilohertz. Voltage and current readings are typically within 1°/o to 400 kHz for sine waves. The power in a 100 kHz square wave may normally be measured within 2%. WIDE MEASUREMENT RANGE AMPLE RESOLUTION The Model 255 provides FOUR full scale current ranges from 5 mA to 5 A, THREE full scale voltage ranges from 20 V to 1000 V., TWELVE full scale power ranges from 100 mW to 5000 W and TWELVE, increased resolution POWER X10 ranges from 10.00 mV to 500.0 W. A full four digit display provides ± 1 digits of resolution for full scale ranges corresponding to 1000, 2000, or 5000 digits. ISOLATED OUTPUTS AND PROGRAMMING The meters have optically isolated, digital options of: A. Parallel, four digit BCD output B. Remote control of FUNCTIONS C. IEEE-488 Talker/Listener Board. The meters have an optional isolated ANALOG output. One volt output for a Full Scale display reading. CURRENT OR VOLTAGE RANGE EXTENSION Full Scale CURRENT ranges down to 50.00 pA or VOLTAGE ranges down to 1.000 V or 2.000 V are possible. External broad­ band shunts or transformers allow CURRENT extension to 50.00 A or 500.0 A. External voltage dividers allow VOLTAGE extension to 3500 V. Full Scale POWER for each case is equal to the VOLTAGE X CURRENT product. M M M * ~ v < $ # # * si DEALS WITH MANY DIFFICULT MEASUREMENTS The Model 255 is ideally suited to measuring almost any non- sinusoidal and/or low power factor waveshape. Typical uses are in connection with SW ITCHING POWER SUPPLIES, TRANSFORMER LOSSES, FLUORESCENT LAMP BALLASTS, R-C Filter RECTIFIER CIRCUITS, SCR CIR­ CUITS, MERCURY-ARC LAMP CIRCUITS, SERVO SYSTEMS, MOTOR TESTING, ULTRASONICS, MOV LOSS TESTING, AUTOMATIC TEST EQUIPMENT, SODIUM LAMP BALLASTS, FERRITE CORE LOSSES, TELEVISION SET LOSSES, AND ELECTRIC AUTOMOBILE EFFICIENCY MEASUREMENTS. EASY TO USE/HARD TO DAMAGE The Model 255 is an all solid state, digital readout instrument. The V-A-W meter is complete, self contained instrument that is easy to use, hard to damage, easy to service, and easy to maintain. LOW CIRCUIT LOADING An imput impedance of five Megohms for the VOLTAGE ter­minals coupled with a full scale voltage drop of 100 millivolts across the CURRENT terminals cause negligible circuit loading or errors in most practical cases. PACKAGING/PROTECTION The Model 255 is housed in a heavy duty aluminum case. The three lowest current range shunts are also diode and fuse pro­tected.

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Service and User Manual
Manual Type:
Service and User Manual
Pages:
98
Size:
3.30 Mbytes (3457534 Bytes)
Language:
english
Revision:
Manual-ID:
255-2940
Date:
1983 01 01
Quality:
Scanned document, all readable.
Upload date:
2017 04 16
MD5:
0d1dd1738aa41251a8ae21bd121f08d5
Downloads:
335

Information

WARRANTY LIST OF ABBREVIATIONS AND CONDENSATIONS USED IN THE MANUAL SPECIFICATIONS I. BASIC FEATURES, CONTROLS, AND CONDENSED OPERATING INSTRUCTIONS 1-1. Introduction 1-2 Basic Controls, Inputs and Outputs 1-3 Special Features 1-4 Condensed Operating Instructions - Voltage and Current 1-5 Condensed Operating Instructions - Power 1-6 Condensed Operating Instructions - Power Factor 1-7 Three Phase Power Measurements II. CALIBRATION : MEASUREMENT AND ADJUSTMENT 2-1 Calibration Equipment and Standards 2-2 Calibration Measurement - Zero 2-3 Calibration Adjustment - Zero 2-4 Calibration Measurement - Current 2-5 Calibration Adjustment - Current 2-6 Calibration Measurement « Voltage 2-7 Calibration Adjustment - Voltage 2-8 Calibration Measurement - Power 2-9 Calibration Adjustment - Power 2-10 Calibration Measurement - Power Factor 2-11 Calibration Adjustment - Power Factor III. THEORY OF OPERATION 3-0 General Operation 3-1 Current Attenuator Board 3-2 Voltage Attenuation Board and Box 3-3 Display Board 3-4-0 Analog Section - General 3-4-1 Amplifier/Multiplier/Input CMOS Switches 3~4-2 Auto-Zero Circuitry (Amplifier/Multiplier) 3-4-3 Analog/Digital Conversion 3-4-4 Power Factor Detector 3-4-5 Square Root Generator 3-4-6 Input Overload Detectors 3-5-0. Clocks and Timing - General 3-5-1. Low Frequency Clock, LFC 3-5-2. High Frequency Clock, HFC 3-5-3. Active 3-5-4. Signal 3-5-5. Reference 3-5-6. Load Latch Pulse, LL, and NOT LL 3-5-7. Polarity Signals 3-6-0. Digital Control Circuitry 3-6-1. Decimal Point, Function, and Full Scale Memories 3-6-2. Input Decoding Circuitry 3-6-3. Drivers for the CMOS Switches in IC11, 12, and 13) 3-7. "Dynamic" Switch Drivers 3-8-0. Over and Under Range Circuitry 3-8-1. Output Over Range 3-8-2. Input Under Range 3-9-0. Power Supplies 3-9-1. +5 V Supply 3-9-2. ± 15 V Supplies 3-9-3. +8 V and -6 V Supplies 3-10. Options, including IEEE-488 bus, analog output, and range extension. IV. REPAIR AND ADJUSTMENT 4-0. Introduction 4-1. Power supply Voltages 4-2. Input Protection 4-3-1. Analog Section - General 4-3-2. Auto-Zero 4-3-3. Integrator/Comparator 4-4. Clock and Timing Circuitry 4-5. Digital Control Logic/Specialized Circuits 4-6-0. Adjustment Procedure After IC Replacement in the Analog Section 4-6-1. Input DC Offset Controls, P2, 12, and 130 4-6-2. Multiplier Crossover Controls 4-6-3. Multiplier DC Offset Controls 4-6-4. Multiplier Linearity 4-6-5. Other Controls V. REPLACEMENT PARTS VI. DIAGRAMS

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