真有效值TrueRMS——唯一的真实测量值

真均方根值数字式电表什么是真均方根值？在理解真均方根值数字式电表之前，我们需要先了解什么是真均方根值。

在电学中，交流电的大小通常以有效值来表示。

有效值是指一个交流电信号在一段时间内的平均值，与直流电的电压或电流大小相同。

但是，我们经常会遇到一些波形复杂的非正弦波形电信号，这时候仅仅用有效值表示电压和电流的大小并不合适。

因此，引入了真均方根值。

真均方根值（简称均方根值，RMS）是指一个交流电信号在一段时间内，其平方值的时间平均值的平方根。

它是一种有效的计算交流电压、电流大小的方法，尤其适用于波形复杂的电路。

真均方根值数字式电表的原理真均方根值数字式电表，简称RMS电表，其原理是通过数模转换器将电流信号转换成数字信号，再经过数字信号处理运算，计算出电流信号的均方根值。

RMS电表适用于测量交流电的电流和电压，相较于传统电表，其测量精度更高，同时还具有抗干扰、自动记录、通讯传输等功能。

真均方根值数字式电表的特点高精度真均方根值数字式电表的测量精度更高，能够有效地测量波形复杂的非正弦信号，大大提高了电力测量的精度。

抗干扰RMS电表在数字信号处理过程中，具有一定的滤波能力，能够有效抑制噪音和干扰信号，使得测量结果更为准确。

自动记录真均方根值数字式电表能够自动记录电能使用情况，有利于电能管理和节省电费。

通讯传输RMS电表相较于传统电表，还具有通讯传输的功能，可以通过网络传输电能使用情况等信息，更加智能、便捷。

真均方根值数字式电表的应用真均方根值数字式电表主要应用于对电能的测量和监测，包括：•工业领域：电能管理、设备监测及控制等；•住宅领域：电子计量表具有小巧、精度高、易读数等特点，适用于家庭电能测量以及室内电能控制等。

总结真均方根值数字式电表的出现，大大提高了电力测量的精度，同时还具有抗干扰、自动记录、通讯传输等功能。

未来随着技术的发展，真均方根值数字式电表的应用范围将不断扩大。

MT-1710N3 3/4 True-RMS Auto Range MultimeterUser’s Manual1st Edition, 2023©2023 Copyright by Prokit’s Industries Co., Ltd.I. INTRODUCTIONThe instrument is a stable and high-performance digital multimeter driven by battery. It uses the LCD with 42mm high to make the readings clearly.The instrument has the function of measuring DCV, ACV, DCA, ACA,Resistance and Capacitance, Frequency, Diode, Triode, Continuity test,Temperature, Auto power off (can be canceled) and backlight function. The instrument takes dual-integral A/D converter as key point, is an excellent tool.It’s an ideal tool for lab, factory, and family.The new generation series of productions add NCV (non-contact ACVinduction measurement) and torch function based on the original function. II.OPEN THE PACKAGE FOR CHECKINGOpen the box, take out the meter, checking the items below if they aremissing or damaging:K type probe (-20℃~250℃) 1pchFE test A d apter 1pcTest leads 1pairUser manual 1pcPlease contact with your supplier if you find out any problems.III.SAFETY NOTESThis series meter meets the standard of IEC61010 (the safety standardsrequest issued by IEC or equal GB4793.1 standards). Read it beforeoperation.1.Input over range is prohibited in each range during the test.2.Voltage less than 36V is safety voltage. When measuring voltage higherthan 36V DC, 25V AC, check the connection, insulation of test leads toavoid electric shock.3.When changing function and range, test leads should be removed fromtesting point.4.Select correct function and range.5.Don’t operate the meter when the battery case and back cover are notfixed6.Don’t input voltage during the resistance measurement.7.Test lead should be removed from testing point before changing thebatteries or fuses and turn off the power.ply with local and national safety regulations, wear personal protectiveequipment (approved rubber gloves, masks and flame-retardant clothing,etc.), to prevent electric shock and arc injury caused by exposure ofdangerous electric conductor.9.Make measurements using only the correct measurement standard class(CAT), voltage and current rated probe, test conductor and adapter.10．Safety symbols:“” exists high voltage“” GND“” Dual Insulation“” Must Refer to Manual“ ” Low BatteryIV.SAFETY SYMBOLSV.SPECIFICATIONSGENERAL SPECIFICATIONS1)Display mode: LCD displaying.2)Max. indication: 3999（3 3/4）, auto polarity indication3)Measuring method: Dual integral A/D conversion4)Sampling rate: Approx. 3times/second5)Over range indication: “OL” displays6)Low battery: The “ ” displays.7)Operating environment: (0 ~ 40) ℃, humidity<75%RH.8)Storage environment:-20℃~60℃，humidity<85%RH9)Power: Four 1.5V AAA batteries, LR0310)Dimension: 186mm×92mm ×52mm.11)Weight: approx. 355g (not include batteries). VI.EXTERNAL STRUCTUR1. Sound alarm indicator light2. LCD display3. Function / range knob4. Measuring input terminal5. Function selection button6. Auto / manual rangeconversion7. Relative value measurement/ flashlight control8. Data hold / backlight control9. NCV induction position10. Flashlight window11. Hang hole12. Screws for fixing the battery box13. Bracket14. Test leads holderVII.LCD DISPLAYVIII.KEY DESCRIPTION1.D ata hold:Short press the "HOLD B/L" button to hold the measuring data on the LCD, and the symbol “HOLD” appears. If you press the key again, the data hold function will be closed, and the symbol will disappear.Warning: to prevent possible electric shock, fire, or personal injury, do not use the data hold function to measure the unknown voltage. When open the HOLD function, the LCD will keep original data when measuring a different voltage.2.B acklight function:Long press the "HOLD B/L" button to turn on the back light of the LCD, and long press this key again to turn off the back light.3.F unction select key (Hz/DUTY SELECT key)At the DC/AC mV、uA、mA、A range, short press the "Hz/DUTY SELECT" key to convert among DCV, ACV, and DCA, ACA for testing; At the diode/continuity test range, short press the "Hz/DUTY SELECT" key to convert the diode and continuity test, the diode range is already set by default. At the ACV range, short press the "Hz/DUTY SELECT" key to cycle switch among the voltage, accompanying frequency, duty cycle. At the temperature range, short press the "Hz/DUTY SELECT" key to convert the Celsius and Fahrenheit; At theFrequency range, short press the "Hz/DUTY SELECT" key to convert the Frequency and duty cycle test.4.A uto / manual range conversionThe auto range is already set by default after the meter is turned on, short press the "RANGE" key, the meter convert to manual range, the “AUTO” symbol on the LCD will disappear. At the manual range mode, the meter starts from the low range, when you press the "RANGE" key, the range change to a higher one, the procedure repeats like this in sequence; long press "RANGE" key to exit the manual range mode, and the LCD displays "AUTO" symbol.5.R elative measurementAt the DC/AC mV、V、uA、mA、A range, capacitance, temperature range, short press the "REL" key to enter the relative measurement mode, and the “REL” symbol appears on the LCD. Short press the “REL” key again, the meter exits the relative measurement mode, and the “REL” symbol disappear s.6.L ightingLong press "REL/ " to turn on/off the Flashlight.7. Cancel the auto power off functionPress the “Hz/DUTY SELECT” key to turn on the meter, the “APO” symbol disappears, and then the auto power off function closed.IX.MEASUREMENT INSTRUCTIONSFirst, please check the battery, and turn the knob to the proper range that you need. If the battery is out of power, the "" symbol willappear on the LCD. Pay attention to the symbol next to the jack for test leads. This is a warning that the voltage and current should not exceed the indicated value.1.DCV and ACV measurement1-1.Set the knob to the mV/ACV/DCV range, and connect the test leads across to the circuit under test. The voltage and polarity of the point which the red test lead is connected are display on the LCD. 1-2.Insert the black test lead to “COM” jack, the red one to “ ”jack.1-3.The auto range is already set by default after the meter is turned on, LCD displays “AUTO” symbol, press the "RANGE" key to convert to manual range, the range 40mV,400mV (only for DC mV/AC mV range), 4V, 40V, 400V, 1000V/750V (DCV/ACV) are optional.1-4.You can get the result from LCD.1-5. At the DC mV/AC mV range, short press the “Hz/DUTY SELECT”key to convert DC/AC mV measurement. The DC mV range is already set by default after the meter is turn on.Note:(1)Do not input a voltage over DC 1000V or AC 750V，otherwise thecircuit might be damaged. At the DC/AC mV range, the input voltage should not exceed 250VDC/ AC RMS.(2)Please keep the test leads away from the circuit after finished yourtesting.(3)When measured voltage is higher than 220V, it’s necessary to wearpersonal protective equipment (such as approved rubber gloves, face masks, and flame-retardant clothing etc.) to prevent the injury from electric shock and arc.2.DCA and ACA measurement2-1.Set the knob to a proper DCA/ACA range, and then connect the test leads to the power or circuit under test in series. The polarity and the current value of this point which connects to the red test lead will display on the LCD.2-2.Insert the black test lead to “COM” jack, the red one to “ ” (max.400mA) or “10A” (max. 10A) jack.2-3.You can get the result from display.2-4.Short press the “Hz/DUTY SELECT” key to convert DCA or ACA, the DCA range is already set by default after the meter is turned on.Short press “RANGE” key to convert to manual range, you can choose 400uA, 4000uA at the uA range, and 40mA, 400mA are optional at the mA range, 4A, 10A are optional at the A range. The auto range is already set by default after the meter is turned on. Note:(1)If the tested current range is unsure beforehand, please start fromthe highest range then find the proper range according to the reading. Do not measure the voltage in the current jack.(2)If the reading displays “OL”，the value is beyond the present range.Now you need to set the knob to the higher range.(3) Be careful when measuring 10A range. Continuous measurement ofhigh current will heat the circuit, even affect the accuracy and damage the meter.(4) When measuring the large current above 10A, it’s necessary to wearpersonal protective equipment (such as approved rubber gloves, face masks, and flame-retardant clothing etc.) to prevent the injury from electric shock and arc.3.Resistance measurement3-1. Set the knob to resistance range, then connecting the test leads to the tested resistance.3-2. Insert the black test lead to “COM” jack, the red one to “ ”jack.3-3. You can read the measurement results from the display.3-4. Auto range method is already set by default after the meter turned on, short press “RANGE” key to convert to the manual range, The range 400Ω, 4KΩ, 40KΩ, 400KΩ, 4MΩ, 40MΩ are optional. Note:(1) If "OL" displays on LCD, it means over range, now you need to setthe range knob to the higher range. When measuring resistance ismore than 1MΩ, the reading may take a few seconds to stabilize.This is normal for high resistance measurement.(2) When the input terminal is under open circuit, the figure "OL" willbe displayed for the overload condition.(3) When checking in-circuit resistance, be sure the power has beenswitched off and all capacitors are fully discharged.4.Capacitance measurement4-1. Set the range knob to a proper capacitance range, connect the test leads to the capacitor under tested (the polarity of red test lead is “+”). 4-2. Insert the red test lead to “ ” jack and the black one to “COM” jack.4-3. You can get the result from LCD.Note:(1) If the LCD displays "OL", it indicates the value is over range. Themaximal range is 100mF.(2) When measuring capacitance, because of lead wire and thedistributed capacitance, there may be some residual reading without connection to capacitance under measured. It will be clearer when measuring small capacitance range. Measuring result is to subtract the residual reading for getting accurate reading. This will not affect the measuring accuracy. You can short press the “REL” key to clear the residual reading of open circuit, then measuring the relative value.(3) When under a large capacitance range, if capacitor is broken orleakage, the LCD will display some value and it’s unstable.(4) Discharge all the capacitance completely before measuring to avoidthe damage of the meter.(5) UNIT: 1mF=1000uF 1uF =1000nF 1nF=1000pF5.TRANSISTOR hFE5-1. Set the knob to “hFE” range.5-2. Insert the adapter to “ ” and “COM” jack, then according tothe NPN or PNP, insert emitter, base and collector to proper jack.5-3. You can get the result from LCD.6.Diode and continuity test6-1. Set the range knob to the “ ” range. The diode range is already set by default after the meter is turned on, short press the “Hz/DUTY SELECT” key to convert the diode and continuity test. Set the black test lead to “COM” jack, and the red one to “ ”jack (the polarity of red test lead is “+”), meanwhile connect the red test lead to the positive of the diode and the black one to the negative. The reading is the approx. value of the diode positive volt drop. If the test leads connect to the reverse polarity of diode, the LCD will display “OL”.6-2. Connect the test leads to two ends of the circuit under tested, if the resistance is lower than approx.（50±20）Ω, the LCD displays “ ” symbol, and the buzzer sounds.7.Frequency measurement7-1.Turn the knob to frequency range, and connect the test leads or shielded cable across the signal source or the load under tested.7-2.Insert the black test lead to the "COM" jack and the red one to the " "jack.7-3.You can get the result from the LCD.7-4.Short press the “Hz/DHTY SELECT” key to convert to duty cycle. Note:(1)When it is over 10V RMS, you can get the result, but we cannot promise the accuracy.(2)It is preferable to use shielded cable for measuring small signal in noisy environment.(3)Be careful when measuring high voltage.(4)Do not input a voltage over DC 250V or AC peak value to avoid damage to the meter.(5)It is auto range at the frequency range, you can test 10Hz ~20MHz.8.Temperature measurementWhen measuring temperature, insert the negative of the thermocouple sensor into the "COM" jack, and insert the positive into the “ ” jack; put the sensing part of the temperature probe on or inside the tested object. Read the value from the LCD which shows as Celsius. Short press the “Hz/DHTY SELECT” key can convert the Celsius or Fahrenheit unit.9.Non-contact voltage induction measurement NCV9-1. Turn the knob to “NCV” range.9-2. NCV induction voltage range is 48V~220V, let the upper position of the meter close to the measured electric AC power line, when the ACV is sensed, the upper red indicator lights of the meter flashing and at the same time a buzzer alarm on, the more close to the AC power line, the more stronger the ACV sensed, the corresponding flashing lights, and the buzzer alarm sounds faster.10.Automatic power on/offTo save power consumption and prolong battery life, the APO automatic shutdown function will be turned on by default after the meter is turned on. If the user does not operate the meter within 14 minutes, the meter will be prompted with 3sounds. If there is still no operation, the meter will automatically turn off the power after a long sound one minute later. Short press “SELLECT” can turn on the multimeter. To cancel APO function, please refer to the instructions in section 8, "key function".X.Technical characteristicsAccuracy: ± (a% × reading + digit)Environment temperature: (23±5) ℃Relative humidity: <75%RH.One year guarantee since production date.10-1. DC VoltageFrequency response: 40Hz-1 kHz. Measurement mode (sine wave): true RMS.Crest factor: CF≦3, adding an additional error of 1% to the reading at CF≧2.AC frequency measurement error: 0.2%+0.02Hz.AC frequency measurement range: 40Hz~1k Hz.AC frequency input sensitivity: 80V~600VFrequency response: 40Hz - 1k HzMeasuring way (sine wave): True RMSCrest factor: CF≤3, when CF≥2, add an additional error of 1% of thereading.10A (The measurement should not be more than 10 seconds); Recovery time is 15 minutes.Overload protection: 250VDC/AC RMS100mFMeasuring range of accuracy: 10% - 100% of the rangeLarge capacitance response time: ≥1uF about 8sMeasurement error does not include lead distribution capacitance.Note: The reading will be zero if the signal is below 3Hz. Input sensitivity: 1VWarning: Do not input voltage at this range. Overload protection: 250V DC/AC RMS Sensor: Type-K thermocouple (Ni-Cr – Ni-Si) banana probeXI.Replace the battery or fuse.1.Move away the test leads from the circuit under test, pull out the test leadfrom the input jack, turn the range knob to the “OFF” range to turn off the power.e a screwdriver to twist off the screws on the battery cover and removethe battery cover and bracket.3.Take out the old battery or the broken fuse, then replace with a new alkalinebattery 9V or a new fuse.4.Close the battery cover and use a screwdriver to tighten the screws on thebattery cover.5.Battery specifications:4 * 1.5V AAA alkaline batteries6.Fuse specifications:mA input fuse "FS1": φ5 * 20mm 400mA 250V10A input fuse "FS2": φ5 * 20mm 10A 250VNote: When the low voltage "" symbol displays on the LCD, the battery should be replaced immediately, otherwise the measuring accuracy will be affected.XII.MAINTENANCE AND CAREIt is an accurate meter. Do not try to modify the electric circuit.1. Pay attention to the waterproof, dustproof and break proof of the meter.2. Please do not store or use it in environment of high temperature, high humidity, high flammability or strong magnetic.3. Please wipe the meter with a damp cloth and soft detergent, and abrasive and drastic solvent such as alcohol are forbidden.4. If do not operate for a long time, should take out the battery to avoid leakage.5. When replacing fuse, please use another same type and specification fuse. 13.Trouble ShootingNo current or temperature inputThis user’s manual is subject to any change without further notice.The content in this user’s manual is deemed correct; if you find any mistake, omission, etc., please contact the manufacturer.We will not be held liable for any accidents or harms caused due to your wrong operations.The functions set forth in this user’s manual shall not be regarded as reasons for applying this product for special purposes.3-3/4真有效值自動量程電錶使用手冊一、產品概述MT-1710N（3 3/4）真有效值自動換檔電錶是一台性能穩定、可靠性高的電池驅動數位萬用電錶。

May 2003 Rev. 3, 4/23 (Simplified Chinese)© 2003-2023 Fluke Corporation. All rights reserved. Specifications are subject to change without notice. All product names are trademarks of their respective companies. 175, 177, 179 True-rms Multimeters终生有限保证Fluke 保证每一台Fluke 20、70、80、170 和 180系列的 DMM，其用料和做工都是终生毫无瑕疵的。

此处所谓的“终生”是指Fluke终止制造本产品后七年，但本项保证期应自产品购买日起至少十年内有效。

本项保证不包括保险丝、可弃置的电池以及因疏忽、误用、污染、改变、意外或非正常状况下的使用或处理所造成的损坏（包括使用产品规范以外的测量所引起的故障或机械部件的正常损耗）。

本项保证仅适用于原购买者并且不得转让。

自购买日起十年内，本保证也包括 LCD。

十年以后直到仪表的终生，Fluke 将以收费的方式更换 DMM 的 LCD（根据当时该组件的成本价格收取费用）。

欲建立原购买者与购买日期的根据，请填妥并寄回产品所附上的注册登记卡，或在上注册产品。

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若产品是从一个国家购买却被送到其它地区修理，Fluke 保留收取修理/更换零件的进口费用的权利。

如果发现产品损坏，请和最靠近您的 Fluke 授权服务中心联络以取得同意退回产品的信息，然后请把产品寄到该服务中心。

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对保修产品的修理或更换，Fluke 将负责回邮的运输费用。

287/289 True-rms Digital Multimeters安全须知访问以注册您的产品并获取更多信息。

警告表示可能对用户造成危险的状况和操作。

XW警告为了防止可能发生的触电、火灾或人身伤害：•使用仪表前请先阅读“安全须知”。

•必须按照本手册的规定使用仪表，否则仪表提供的保护措施可能会失效。

•切勿使用已损坏的仪表。

使用仪表之前，请检查仪表的外壳，检查是否存在裂纹或塑胶缺损。

特别注意接头周围的绝缘。

•使用仪表之前，请确定电池盖已经闭合并且扣紧。

•打开电池盖之前，请先取下仪表上的测试导线。

•检查测试导线的绝缘是否损坏或导线金属是否裸露在外。

检查测试导线是否导通。

若导线有损坏，请更换以后再使用仪表。

•在端子间或任何一个端子与接地点之间施加的电压不能超过仪表上标示的额定值。

•在外盖取下或机壳打开时，请勿使用仪表。

•对 30 V 交流（有效值）、42 V 交流（峰值）或 60 V直流以上的电压，应格外小心。

这些电压有电击危险。

•必须使用本手册指定的替换保险丝。

•测量时，必须使用正确的端子、功能档和量程档。

•不要单独工作。

•测量电流时，应先切断电路的电源，再把仪表连接到电路上。

记住：仪表必须和电路串联。

•在进行电气连接时，先连接公用测试导线，然后再连接带电测试导线；拆线时，先拆除带电测试导线，然后再拆除公用测试导线。

•若仪表工作失常，请勿使用。

产品的保护功能可能受损。

若有疑问，应将仪表送修。

PN 4271782 (Simplified Chinese)August 2012 Rev. 1, 1/18© 2012-2018 Fluke Corporation. All rights reserved.All product names are trademarks of their respective companies. Specifications are subject to change without notice.•切勿在有爆炸性的气体、蒸汽或灰尘附近使用仪表。

第 21 卷 第 7 期2023 年 7 月太赫兹科学与电子信息学报Journal of Terahertz Science and Electronic Information TechnologyVol.21，No.7Jul.，2023一种真有效值测量方案设计与验证刘宁庄1，段富才1，文迪雅1，许龙2(1.西安科技大学电气与控制工程学院，陕西西安710600；2.中国计量大学理学院，浙江杭州310018)摘要：针对目前国内真有效值(RMS)测量芯片依赖进口的问题，提出了一种基于现场可编程门阵列(FPGA)的数字式高精确度的真有效值测量方案。

首先利用FPGA设计有限长单位冲击响应滤波器(FIR)对AD采样后的数据进行滤波，然后采用改进的有效值计算式计算信号的真有效值，最后取连续8个周期真有效值的平均值作为最终的测量结果。

通过设计串行的开方运算、除法运算的算法，降低FPGA的使用资源。

经过样机实际测试表明，测量结果与信号真值的相对误差低于0.5%。

该方案测量精确度高，一致性好，使用资源少，对于真有效值数字测量芯片的设计和真有效值测量具有一定的参考价值。

关键词：数字测量；真有效值；现场可编程门阵列；冲击响应滤波器；开方运算；除法运算中图分类号：TM932 文献标志码：A doi：10.11805/TKYDA2020738Design and verification of a true root mean square measurement schemeLIU Ningzhuang1，DUAN Fucai1，WEN Diya1，XU Long2(1.School of Electric and Control Engineering，Xi'an University of Science and Technology，Xi'an Shaanxi 710600；2.College of Science，China Jiliang University，Hangzhou Zhejiang 310018)AbstractAbstract：：A high-precision and digital true root mean square measurement method based on Field Programmable Gate Array(FPGA) is presented. Firstly, FPGA is employed to design Finite ImpulseResponse(FIR) filter to filter the AD sampled data. Furthermore, the improved RMS formula is adopted tocalculate the true RMS of the signal. The mean value of the true RMS value of eight consecutive cycles istaken as the final measurement result. By designing the algorithms of serial extraction and divisionoperations, the use of FPGA resources is reduced. The actual test of the prototype shows that the relativeerror between the measurement results and the true value of the signal is less than 0.5%. The solutionhas high measurement accuracy, good consistency, and less resources, which has certain reference valuefor the design of the true RMS digital measurement chip.KeywordsKeywords：：digital measurement；true root mean square；Field Programmable Gate Array；Finite Impulse Response filter；square root operation；division operation测量交流信号的真有效值对分析信号的功率以及其他参数都有重要意义[1-4]。

MT-17053-1/2 True-RMS MultimeterUser’s Ma Edition okit’s Industries Co., Ltd.nual,t by Pr 1st ©2014 CopyrighOPERATION MANUALSUMMARIZEThe instrument is a stable digital multimeter driven by battery. It comes with 20mm high LCD to make reading more clear. Backlight display and overload protection make it convenient to use .This instrument features multi functions for measuring DCV, ACV, DCA,ACA, resistance, capacitance, diode,continuity and frequency., The instrument utilizes a dual-integral A/Dconverter as a key feature and is an excellent tool. It is portable and Ideal for lab, factory and field use.SAFETY NOTEThe meter meets the standards of IEC1010.Please read the operation manual carefully before operation.1．Do not input anything over a range limit.2．Voltage below 36V is safe. To avoid electric shock, check whether the test leads are connected correctly, whether the insulation is good when measuring over 36DCV or 25ACV.3．Remove the test leads when changing function and range.4．To select correct function and range, make sure the range limit setting is correct. Start with higher limits and work down to correct level if uncertain.5．Do not operate the meter if battery case and back cover is not properly fixed.6．Do not input voltage when measuring resistance.7．Remove test leads from test point and turn off the power before replacing battery and fuse.8． SAFETY SYMBOLS“”DANGEROUS VOLTAGE EXISTS，“” GND，“”DUAL INSULATION“”THE OPERATOR MUST REFER TO THE MANUAL ，“”LOW BATTERYCHARACTERISTIC1 GENERAL1.1 Display:LCD displaying.1.2 Max. displaying: 1999（3 1/2digit）auto polarity indication.1.3 Measuring method: dual slope A/D conversion.1.4 Sampling rate: approx. 3 times/second.1.5 Over range indication: the MSD displays“OL”.1.6 Low battery indication:“” appears.1.7 Operation environment: （0～40）℃，R.H.<80% .1.8 Power：1.5V AAA×2pcs1.9 Size: 150×73.5×35mm1.10 Weight: approx. 170g（not includes battery）.1.11 Accessories:operation manual,holster, test leads.2 TECHNICAL CHARACTERISTIC2.1 Accuracy:±(a%× rdg ＋d) at (23±5)℃，R.H.<75%，one year guaranteedfrom the production date.2.2 TECHNICAL DATA 2.2.1 DCVRANGE ACCURACY RESOLUTION200mV 100uV2V 1mV 20V 10mV200V±(0.5%+3) 100mV 600V ±(1.0%+10) 1VInput resistance: All ranges: 10 M ΩOverload protection: 250V DV or AC peak value at 200mV range.600V DC or AC peak value at other ranges.2.2.2 ACV True RMS measurementAccuracy Range 40Hz-200Hz 200Hz-1kHzResolution 2v 1mV 200v ±(0.8%+5) ±(0.8%+5) sine and triangularwave 100mV600V ±(1.2%+10) ±(1.2%+10)sine and triangular wave±(8.0%+15) other wave 1VInput impedance ：All ranges 10M ΩOverload protection ：250V DC or AC peak value at 200mV ,600V DC or AC peak value at other ranges.Frequency response: 40Hz-1kHzDisplay: True RMS2.2.3 DCARANGE ACCURACY RESOLUTION20mA 10uA 200mA ±(1.2%+8) 100uA10A ±(2.0%+5) 10mAMax. input volt drop: 200mV;Max. input current: 10A （the test time should be within 10seconds ）Overload protection: 0.2A/250V fast-blow fuse, no protection at10A.2.2.4 ACA True RMS measurementAccuracy Range 40Hz-200Hz 200Hz-1kHzResolution 200mA ±(1.5%+15) ±(1.5%+15)sine and triangular wave100uA10A ±(3.0%+10) ±(3.0%+10)sine and triangular wave±(8.0%+15) other wave 10mAMax. measuring voltage drop ：200mV.Max. input current: 10A (less than 10 seconds).Overload protection ： 0.2A/250V fuse ；no protection at 10A.Frequency response: 40Hz-1kHz.Display ：True RMS2.2.5 RESISTANCE （Ω）RANGE ACCURACY RESOLUTION200Ω ±(0.8%+5) 0.1Ω20k Ω 10Ω 200k Ω ±(0.8%+3) 100Ω20M Ω ±(1.0%+25) 10k ΩOpen voltage: less than 3V.Overload protection: 250V DC or AC peak value.NOTE:1. At 200Ω range, the test leads should be short-circuited, andmeasure the lead to lead resistance, then, subtract from the realmeasurement.2. It is normal for reading to be slow when measured value is above 1M Ω, please read it after the display value stabilizes.2.2.6 CAPACITANCE (C)RANGE ACCURACY RESOLUTION20nF 10pF200nF 100pF2uF ±(3.5%+20) 1nF20uF 10nF200uF 100nF2000uF ±(5.0%+10) 1uFOverload protection: 250V DC or AC peak valueNOTE: when over range, it can keep on measuring, "OL" will notshow on LCD and the value is for reference only2.2.7 FREQUENCYRANGE ACCURACY RESOLUTION10Hz 0.001Hz 100Hz 0.01Hz 1kHz 0.1Hz10kHz 1Hz100kHz 10Hz2MHz±(1.0%+10)100HzInput sensivity:1V RMS , overload protection : 250V DC or ACpeak value(less than 15 seconds)NOTE: when over range, it can keep on measuring, "OL" will notshow on LCD and the value is for reference only2.2.8 DIODE AND CONTINUITY TESTRange Displaying value Test conditionPositive voltagedrop of diodeThe positive DCcurrent is approx.1mA，negative voltageis approx. 3VBuzzer sounds ,the resistance isless than(50±20)Ωopen voltage is approx.3VOverload protection: 250V DC or AC peak valueWarning: DO NOT input any voltage at this range for safety!3 OPERATION3.1 Front panel description3.1.1 LCD: display the measured value.3.1.2 Power/auto power off key:turn on/offthe power and auto power off.3.1.3 Hold/backlight/function selecting key:turn on/off hold and backlight key.3.1.4 Range knob: selecting measuringfunction and range .3.1.5 GND.3.1.6 10A current test jack.3.1.7 “+” pole jack of voltage 、resistance、diode、capacitance and resistance.3.2 VOLTAGE MEASUREMENT3.2.1 Insert the black test lead to “COM” jack, the red one to V/Ω/Hzjack.3.2.2 Set the range knob to a proper DCV/ACV range, If the measuredvoltage is unsure beforehand, set the range knob to the highestrange,then reduce it gradually until get the highest resolutionreadings.3.2.3 Apply the test leads to the test point ,the LCD displays themeasured voltage value.NOTE:a. If LCD displays “OL”, it means over range, set the range knob to ahigher range.b. Do not input a voltage over 600V DCA or 600V ACV, the test leadsshould be off the test point when switching the function and range.c. Do not touch a high voltage circuit when measuring high voltage .3.3 CURRENT MEASUREMENT3.3.1 Insert the black test lead into “COM” jack, the red one to “mA” or“10A”jack.3.3.2 Set the range knob to a proper DC or AC mA/A range, If themeasured voltage is unsure beforehand, set the range knob to thehighest range, then reduce it gradually until get the highestresolution readings.3.3.3 Connect the test leads to the circuit under test, the LCD displaysthe measured voltage value.NOTE:a. If LCD displays “OL”, it means over range, set the range knob to ahigher range.measuringcurrent,mA hole should not exceed 200mA,10Ab. Whenhole should not exceed 10A(test time should be less than 10 sec.)3.4 RESISTANCE MEASUREMENT3.4.1 Insert the black test lead to “COM” jack and the red one to“V/Ω/Hz” jack.3.4.2 Set the range knob to a proper resistance range, connect the testleads across to the resistance being measured.NOTE:a. If the resistance value being measured exceeds the max value ofthe range selected, LCD displays "OL", , set the range knob to ahigher range. When the resistance is over 1MΩ, the meter may takea few seconds to stabilize. This is normal for high resistancereadings.b. When input terminal is in open circuit, overload displays.c. When measuring in-line resistance, be sure that power is off and allcapacitors are discharged completely.d. Do not input any voltage at this range.3.5 CAPACITANCE MEASUREMENT3.5.1 .Insert the red test lead to “V/Ω/Hz”terminal and the black one to“COM” jack.3.5.2 Set the range knob to a proper capacitance range, connect the testleads to the capacitor being measured（note: the polarity of red testlead is “+”）.NOTE:a. If the resistance value being measured exceeds the max value ofthe range selected, LCD displays "OL".b. Before measuring, LCD display might not be zero, the residualreading will decrease gradually and should be disregarded.c. When measuring large capacitance, LCD may display an unstablevalue due to creepage or breaking.d. Discharge all capacitors completely before capacitancemeasurement to avoid damage.e. Do not input any volt at this range.f. This range is for automatic range test,measuring the range from10nF to 2000uF.g. UNIT: 1mF=1000uF 1uF =1000nF 1nF=1000pF3.6 FREQUENCY MEASUREMENT3.6.1 Apply the test lead or shield to cable to “COM” or ““V/Ω/Hz”terminal.3.6.2 Switch the knob to frequency range,and connect the test leadsacross the signal source or the measured load.NOTE:a. When input is 10Vrms or less,a reading is possible but maybeover-range.b. Shielded cable is recommended when measuring small signalsunder noisy conditions.c. Be careful when measuring high volt circuit.d. Do not input a voltage over DC 250V or AC peak factor to avoiddamage to the meter.e. This range is for automatic range test,Measuring the range from10Hz to 2MHz3.7 DIODE AND CONTINUITY TEST3.7.1 Insert the black test lead to “COM” terminal and the red one to“V/Ω3.7.2positive volt drop.3.7.3 Connect the test leads to two points of the measured circuit, ifbuzzer sounds, the resistance is lower than approx.（50±20）Ω.3.8 DATA HOLDPress the “HOLD/BL”,LCD displays “HOLD”,the present value is held on LCD,press it again, the function is cancelled.3.9 AUTO POWER-OFFAfter not working about 15minutes, the meter will be changed to sleepmode. Press “POWER APO” key for 2 seconds to restart the power. Press the “POWER APO” key for 2 seconds to cancel the function of auto power off and “APO” icon will disappear from LCD; press it again for 2 secondsto restart the auto power off function and “APO” appears on LCD.3.10 POWER ON/OFFPress “POWER APO” key for 2 seconds to turn on the power and themeter is in working mode,Press “POWER APO” key again to turn it off.3.11 BACKLIGHT INDICATIONPress “POWER BL” key to turn on the backlight; press it again to turn off.If the meter stops working more than 15sec, the backlight will auto poweroff.4 MAINTENANCEDO NOT tamper with the circuit it’s a precision meter and should only be serviced by factory personnel.4.1 Do not operate or store the instrument in high temperature or highhumidity place and do not work closed to flammability substance or explosive or strong magnetic field.4.2 Use the damp cloth and soft solvent to clean the meter, do not useabrasive and alcohol.4.3 If not operated for a long time, take out the battery.4.3.1 When LCD displays “ ” symbol, replace the battery as below:4.3.1.1 Take out of the holster and drop out the battery case.4.3.1.2 Take out the battery and replace a new one. It’s better touse alkaline battery for long time use.4.3.1.3 Fix the battery case and replace the holster.4.3.2 Replacing fusePlease use the same type and specification fuse as replacement.5 TROUBLE SHOOTINGIf the meter does not work properly, check the meter as follows:CONDITIONS WAYTOSOLVENO DISPLAYING ●Power is off●Replace batterysymbol displays ●Replace battery NO CURRENT INPUT ●Replace fuse BIG ERROR ●Replace batteryMT-17053-1/2真有效值數位電錶使用手冊一. 產品概述MT- 1705 3-1/2真有效直自動換檔電錶是一台性能穩定、可靠性高的電池驅動數位萬用電錶。

为了便于查找问题的根源，您需要准确测量有效值电流，并将其与相关部件的额定有效值进行比较。

术语“rms ”表示“均方根”，用于计算任何交流波形的有效值（或热值）。

在电气方面，交流有效值等于特定电压或电流波形的直流热值。

保险丝、母线、导线以及断路器热敏元件等电气部件的额定电流均为有效值电流，因其主要限制均与散热量有关。

如果您正在测量线性负载，例如标准感应电机、电阻加热器或白炽灯，您可以使用平均响应测量工具轻松测得准确的有效值。

但是，如果电路中存在非线性负载，则需要使用真有效值测量工具才能测得准确的有效值，否则您的测量结果可能偏低多达 40%。

平均响应与真有效值 平均响应工具（例如 Fluke T5 电气测试仪）假设测量的是纯正弦波并依此计算相应数值。

此类工具使用一种快捷的方法获得交流波形的整流平均值，并将该数字乘以1.11 来计算有效值。

结果不是真正的有效值，而是基于纯正弦波假设的计算值。

如果您测量具有纯正弦波的负载，则此方法非常准确。

但是，如果您测量具有非线性负载的电路，则平均响应仪表的读数可能偏离多达 40%。

这会延误您对问题的准确诊断，并可能导致您更换不需要更换的部件。

真有效值测量工具配有一个可根据有效值公式计算热值的内部电路。

无论是何种电流波形，这种方法都可以给出正确的热值。

因此，您能够准确地测量真实负载电流，以确定电路是否出现故障或过载，或者问题是否与负载本身有关。

下表举例介绍了平均响应工具和真有效值工具如何响应不同的波形。

对电气设备故障或烦人的跳闸进行故障排除时，您需要知道的关键细节之一是相关电路是否连接了非线性负载。

非线性负载来自计算机、电子控件、变速驱动器和节能照明（比如 LED 照明）等设备，以及来自以短脉冲形式而非平滑正弦波来消耗电流的高效 HVAC 系统。

这些脉冲使谐波电流流回电力系统的其他部分并产生非正弦波形。

结果出现过热和失灵，最终整个系统发生故障。

图中所示的两款测试仪均在测量同一个谐波失真负载。

真有效值转换应用指南第2版作者：Charles Kitchin、Lew Counts©1986 Analog Devices, Inc. 版权所有。

美国印制。

保留所有权利。

未经版权所有人许可，不得以任何形式复制本出版物或其中任何部分。

Analog Devices, Inc.确信其所提供的信息是准确而可靠的。

但是，Analog Devices, Inc.对使用这些信息不承担任何责任。

Analog Devices, Inc.不保证本文所描述的电路互连不会侵犯现有或将来的专利权，而且本文所述内容并未默示授予许可根据本文内容制造、使用或销售设备。

规格和价格如有更改，恕不另行通知。

G803a-30-5/86简介本应用指南阐述集成电路真有效值转换器AD536A、AD636和AD637的工作原理，并介绍了这些器件的许多实际应用电路。

这些集成电路具有低成本、低功耗和高（激光调整）精度特性，使得真有效值（RMS）计算成为一项实用、可行的技术，可用来获取波形的功率测量值或标准偏差。

以前，采用模块式、混合式、或分立式器件的真有效值（RMS）转换器不仅成本高，而且相对复杂，往往使“真有效值”成为只能在实验室利用专门仪器得到的稀罕之物。

除具体应用之外，本指南还简要说明了真有效值的数学内涵，并将真有效值方程式的各种实现方法做了比较，例如：热计算、隐式计算、显式计算、以及更常用的“均值”整流值非真有效值检波器。

我们希望这些背景信息有助于消除有关真有效值计算的一些神秘感，帮助设计人员以创新的方式熟练运用ADI公司的真有效值转换器，以及一般意义上的真有效值测量技术。

我们对以下人士给予的支持和帮助表示衷心感谢：以Marie Etcheils为首的ADI公司通信服务艺术部门全体员工（Lea Cook、Joan Costa、Terri Dalton、Wendy Geary、Ernie Lehtonen、Sue Lortie、Cammy O'Brien）对本指南中的图表进行了精心排版处理；Julie Williams 输入并校对了本指南手稿；Andy Wheeler、Eric Janson、Paul Brokaw、Doug Grant仔细审阅了本指南的内容；Chuck Ayres对噪声测量提出了真知灼见；Don Travers和ADS应用小组提供了许多实用建议；以及Rieh Frantz和Jeff Riskin在这项漫长的工作中给予了支持和鼓励。

UT804使用说明书序 言尊敬的用户：您好！感谢您选购全新的优利德仪表，为了正确使用本仪表，请您在本仪表使用之前仔细阅读本说明书全文，特别有关“安全注意事项”的部分。

如果您已经阅读完本说明书全文，建议您将此说明书进行妥善的保管，与仪表一同放置或者放在您随时可以查阅的地方，以便在将来的使用过程中进行查阅。

1目录项目 页一、概述二、开箱检查三、安全工作准则安全四、国际电气符号五、综合指标六、外形结构图七、旋钮开关及按键功能八、LCD显示器九、测量操作说明 1、直流电压测量 2、交流电压测量 3、直流mV电压测量 4、交直流电流测量 5、电阻测量 6、电路通断测量 7、二极管测量 8、电容测量 9、频率/占空比测量 10、温度测量3345567810101112131618192021222项目 页11、(4～20mA)%测量12、自动关机功能十、技术指标1、直流电压测量2、交流电压测量3、直流电流测量4、交流电流测量5、电阻测量6、电容测量7、频率测量8、占空比9、二极管测量10、电路通断测量11、温度测量12、(4～20mA)% 测量十一、保养和维修1、一般的保养和维修2、更换保险丝管3、更换电池十二、RS232C接口1、RS232C接口连接2、USB接口连接232432323334353637383939394041424242434444454三、安全工作准则安全本仪表严格遵循GB4793电子测量仪器安全要求以及IEC61010-1安全标准进行设计和生产。

符合双重绝缘过电压标准CAT I 1000V、CAT II 600V和污染等级Ⅱ的安全标准。

如果未能按照有关的操作说明使用仪表，则可能会削弱或失去仪表为你提供的保护。

使用前要检查仪表和表笔，谨防任何损坏或不正常的现象，如果发现任何异常情况：表笔裸露、机壳损坏、液晶显示器无显示等等，请不要使用。

严禁使用没有后盖和后盖没有盖好的仪表，否则有电击危险。

目录目录第一章 安全信息◎仪表安全标准…………………………………………………………………………………………………………….. ◎警告……………………………………………………………………………………………………………………….. ◎有限担保及其责任范围………………………………………………………………………………………………….. 第二章 仪表介绍◎特点……………………………………………………………………………………………………………………….. ◎前面板说明……………………………………………………………………………………………………………….. ◎后面板说明……………………………………………………………………………………………………………….. ◎功能描述………………………………………………………………………………………………………………….. 第三章 操作方法◎交流伏特/分贝测量...................................................................................................................... ◎直流伏特/直流伏特＋交流伏特测量................................................................................................. ◎直流毫伏/交流毫伏/直流毫伏＋交流毫伏测量.................................................................................... ◎逻辑频率/占空比测量................................................................................................................... ◎二极管测量................................................................................................................................ ◎电阻/通断测量............................................................................................................................ ◎电容测量................................................................................................................................... ◎直流微安/交流微安/直流微安＋交流微安测量.. (I)1 123 8 10 13 14 15 16 17 18 19 204目录◎直流毫安/交流毫安/直流毫安＋交流毫安测量………………………………………………………………………… ◎直流安培/交流安培/直流安培＋交流安培测量………………………………………………………………………… ◎线性频率测量………….…………………………………………………………………………………………..…….. ◎相对值测量………………………………………………………………………………………………………..……… ◎最大值/最小值/最大值 － 最小值测量…………………………………………………………………..……………. ◎数据保持…………………………………………………………………………………………………………..……… ◎数据存储与回放………………………………………………………………………………………………….……… ◎与计算机RS －232C 口的连接………………………………………………………………….……………………… 第四章 技术指标◎一般特性…………………………………………………………………………………………………………..……… ◎量程和精度………………………………………………………………………………………………………………. 第五章 维护◎更换保险丝………………………………………………………………………………………………………………. ◎仪表校准………………………………………………………………………………………………….………………. ◎其它……………………………………………………………………………………………………….……..………..II21 22 24 26 31 32 32 23 24 24 24 25 27第一章安全信息第一章仪表安全标准这款数字多用表是根据国际电工安全标准IEC1010-1对电子测试仪器和手持式数字多用表的安全要求而设计制造的。

真RMS-DC变换器AD736/AD737AD736/AD737是AD公司推出的真有效值直流变换器。

和以往的有效值测量技术不同,真有效值直流变换可以直接测得各种波形的真实有效值,它不是采用整流加平均测量技术,而是采用信号平方后积分的平均技术。

采用AD736/AD737可以简化仪器的设计,增加信号测量品种,并且灵敏度、精确度也大大改善。

本文讨论了真RMS测量技术的工作原理,并给出了AD736/AD737的典型应用电路。

AD736/AD737；真RMS-DC；测量；仪表;AD737JN；The AD737* is a low power, precision, monolithic true rms-to-dc converter. It is laser trimmed to provide a maximum error of ±0.2 mV ±0.3% of reading with sine wave inputs. Furthermore, it maintains high accuracy while measuring a wide range of input waveforms, including variable duty cycle pulses and triac (phase) controlled sine waves. The low cost and small physical size of this converter make it suitable for upgrading the performance of non-rms precision rectifiers in many applications. Compared to these circuits, the AD737 offers higher accuracy at equal or lower cost.The AD737 can compute the rms value of both ac and dc input voltages. It can also be operated ac-coupled by adding one external capacitor. In this mode, the AD737 can resolve input signal levels of 100 μV rms or less, despite variations in temperature or supply voltage. High accuracy is also maintained for input waveforms with crest factors of 1 to 3. In addition, crest factors as high as 5 can be measured (while introducing only 2.5% additional error) at the 200 mV full-scale input level.The AD737 has no output buffer amplifier, thereby significantly reducing dc offset errors occurring at the output, which makes the device highly compatible with high input impedance ADCs.Requiring only 160 μA of power supply current, the AD737 is optimized for use in portable multimeters and other battery-powered applications. This converter also provides a power-down feature that reduces the power-supply standby current to less than 30 μA.T wo signal input terminals are provided in the AD737. A high impedance (1012 Ω) FET input interfaces directly with high R input attenuators, and a low impedance (8 kΩ) input accepts rms voltages to 0.9 V while operating from the minimum power supply voltage of ±2.5 V. The two inputs can be used either single ended or differentially.The AD737 achieves 1% of reading error bandwidth, exceeding 10 kHz for input amplitudes from 20 mV rms to 200 mV rms, while consuming only 0.72 mW.The AD737 is available in four performance grades. The AD737J and AD737K grades are rated over the commercial temperature range of 0°C to 70°C. The AD737JR-5 is tested with supply voltages of ±2.5 V dc. The AD737A and AD737B grades are rated over the industrial temperature range of −40°C to +85°C. The AD737 is available in three low cost, 8lead packages: PDIP, SOIC_N, and CERDIP.Product Highlights1. Capable of computing the average rectified value, absolute value, or true rms value of variousinput signals.2. Only one external component, an averaging capacitor, is required for the AD737 to perform true rms measurement.3. The low power consumption of 0.72 mW makes the AD737 suitable for battery-powered applications. 1. 真RMS-DC变换器目前市场上的万用表大多采用简单的整流加平均电路来完成交流信号的测量,因此这些仪表在测量RMS值时要首先校准,而且用这种电路组成的万用表只能用于指定的波形如正弦波和三角波等,如果波形一变,测出的读数就不准确了。