仪表系统试验方案(中英)

仪表系统试验方案

Test Scheme of Instrument System

1、编制说明：

1.1、仪表系统试验是在仪表设备安装、管路、线路及施工完成后，中间交接前仪表工程施工的最后一道工序，是对已完仪表工程的检验，是仪表系统正常投运的保障。为了较好的完成仪表系统试验，特编制此方案。

1.2、本方案是以常规控制为例来编写的，如为DCS或PLC控制系统，系统试验现场部分可参见此方案。如为现场总线系统，则需另外编写。

2、编制依据：

2.1、施工合同及协议。

2.2、工程施工图及相关设计文件。

2.3、产品说明书。

2.4、现行的《自动化仪表工程施工及验收规范》。

2.5、现行的《自动化仪表安装工程质量检验评定标准》。

2.6、现行的《化学工业大、中型装置试车工业规范》。

3、工程概况（包括：工程名称、范围、地点、规模、特点、工期要求等）：

工程量见下表

4、仪表系统试验的一般规定：

General Description of Instrument system test:

4.1、系统试验应具备下列条件：

Conditions of system test as following：

4.1.1、仪表设备已经过单体校准试验，并已安装完毕，规格型号符合设计要求。

Instrument has been carried out single-calibration and installed. Its specification and type shall be compliance with design requirement.

4.1.2、取源部件位置适当，测量管路安装正确无误，已吹扫、试压

合格。

The position of sampling-source components shall be proper. Impulse piping shall be correctly installed. Blowing and pressure test have been successfully completed.

4.1.3、气动信号管符合设计要求，已吹扫，气密性试验合格，已通入清洁、干燥、压力稳定的仪表空气

Pneumatic signal pipe shall be compliance with design requirement. Blowing and airtight test is OK, and the piping has been full of clean, dry and steady-pressure instrument air.

4.1.4、电气回路已进行校线及绝缘检查，接线正确，端子接线牢固，接触良好。

Wiring and insulation of electric-loop have been inspected. Terminal connection is tight, correct and well contact.

4.1.5、接地系统完好，接地电阻符合设计要求。

Earthing system is well and its resistance shall comply with design requirement.

4.1.6、电源、电压、频率、容量符合要求，总开关、各分支开关和保险丝容量符合图纸要求。

Power supply, voltage, frequency and capacity should meet request. Main switch, sub-switches and fuse capacitance shall accord with drawing requirement.

4.1.7、如果监视及控制部分为DCS系统及PLC，则系统本身应已送电，硬件及软件试验检查已完成（DCS系统调试方案第一、二层次已完成）；如果监视及控制部分为常规仪表，应具备送电条件。

If monitoring and control sections including DCS and PLC, system itself shall been energized; Software and hardware test and checking have been finished. If they are general instrument, energizing condition has existed.

4.2、每个系统试验之前应按系统中仪表要求的时间进行通电预热。

Carrying out energizing to preheat according to specified time of system instrument before test for system.

4.3、做检测系统试验时，试验点一般应按设计量程（或信号）的0%、50%、100%、100%、50%、0% 三点上行、下行试验，确认显示单元显示范围符合设计要求，显示的最大误差值及回差值应小于该系统的系统误差值（系统误差为该系统参与试验的各单台仪表允许误差平方和的平方根值）。

When test for detecting system, choosing three points up and down run test of design range 0%, 50%, 100%, 100%, 50%,0%.Verifying indication scope of indicating units correspond with design. The maximum error and returning error shall be less than systematic error. (Systematic error is the square root of tolerance error square sum of every single-instrument being participated in system test.)

4.4、联锁报警试验时，应首先确认联锁报警设定值，试验误差不大于允许的系统误差值。

When acting interlock alarm test, verifying interlock alarming setting value firstly. Test error shall not be greater than allowance.

4.5、每个系统试验完成后，应把如线路、箱盖、槽盖、管路、阀门等在试验中改变过状态的设备及线路恢复到原始状态或合理的状态。

After system has been tested, those equipments whose condition has changed during test such as wire-route, box covers, channel covers, pipelines and valves shall been regained to primary or reasonable condition.

4.6、系统试验是仪表施工的最后一道工序，是施工单位与建设单位进行中间交接的过程，因此，系统试验人员应会同甲方、监理、工艺操作人员共同进行试验，并按交工表格要求做好系统试验记录。

System test is the last process of instrument construction and intermediate acceptance between contractor and client. Therefore, Instrument regulation worker together with client, supervisor, and process operators, and record system test recorder according to handing over sheet.

4.7、系统试验中使用的标准仪器，精度应符合要求，并在有效使用期内。

Precision of standard instrument applied in system test shall be accorded with requirement, and be within inspecting valid period.

5、试验方法：Test method:

5.1、压力检测回路试验：

Pressure detecting Loop Test:

5.1.1、气动仪表检测回路：

Pneumatic instrument measurement loop:

把压力信号发生器（带压力显示）压力输出口和气动压变的测量口连接，气动压变的输出口接三通连接标准压力显示仪表，接通气动压变及气动显示仪的气源按设备规格表要求，使信号发生器缓缓依次输出变送器测量范围的三点上下行值，分别记录试验值（显示仪表读数应以表针不再移动为准），显示仪表的试验误差值应符合要求。

Connect pressure outlet of pressure signal generator with measurement mouth of pneumatic pressure transformer. Join output of pneumatic pressure transformer to tee and connecting standard pressure transformer and indicator. According to equipment specification table, make signal generator output slowly and sequentially three up and down going points’values within range of transmitter, and write down test result apart. (Indication instrument pointer shall not move.) Test error of indication instrument shall accord with requirement.

5.1.2、电动仪表检测回路

Electrical instrument measurement loop:

把压力信号发生器（带压力显示）压力输出口和压变的测量口连接，把标准电流表串联到系统回路里，检测变送器的输出，按设备规格表要求量程，使信号发生器缓慢依次输出变送器测量范围的三点上下行值，分别记录试验值，显示仪表的试验误差值应符合要求。

Connecting pressure output of signal generator (with pressure indication) with measurement mouth of pressure transformer. Shunting standard current meter into system loop Inspecting and measurement transmitter output, selecting range in term of equipment specification table, making signal generator output slowly three up and down points’ values of transmitter measurement limit one after another, taking down test result separately. And test error of indication instrument shall correspond with requirement.

5.1.3、智能压力变送器作为测量仪表：

Taking intelligent pressure transmitter as measured instrument: 在进行系统试验前，应在DCS系统调入智能变送器组态在线自检，检查该变送器位号、单位、量程及温度应符合要求，然后做修改参数试验。

然后在现场用手持式通讯器强制变送器输出量程的0%、50%、100%、50%、0%，并在DCS检查其精度是否符合要求。

Prior to system test, carrying out inline self-inspection by intelligent manual-operator, at the place where system goes through control room terminal. Connect and check transmitter tag No., unit and range compliance with requirement and field situation. And then, modify parameter to test and inspect location-output current. After finishing test, doing systematic simulation test.

5.2、温度检测回路试验：

Test of Temperature Checking and Measurement Loop:

5.2.1、线路电阻的测量与配制：

Measure and confect a description of circuit resistance.

a、热电阻测量系统（不带温变）：

系统试验之前应首先把温度显示单元后的信号输入线拆下，信号电缆从热电阻接线端子上拆下分别短接，测量线路阻值分别除2，该阻值加上显示单元后接线端子上每根线上的锰铜无感调整电阻值应和显示单元标尺板上标明的外接线路电阻值相等，允许误差为±0.1Ω。

RTD measurement system (without temp-changer):

Dismount signal input-line which be behind temp-indication unit before test. Disconnecting signal cable from connection terminal of RTD and short-connection respectively. Measure circuit resistance and divide 2 apart. The resistance added that of manganese-copper non-induction regulation of every wire on connection terminal behind display unit shall be equal to external-connection resistance noted on display unit scale board. Deviation error is ±0.1Ω.

b、由热电偶、动圈仪表组成的测温系统：

Temperature measurement system composed of thermocouple

movable-ring:

系统试验之前首先从动圈仪表后拆下输入线，测量线路电阻值，该阻值加上锰铜无感调整电阻值应和动圈表标尺板上标明的外接线路电阻值相等，允许误差为±0.1Ω。

Prior to test, at first, disconnect input wire from back of movable-ring instrument, and measurement circuit resistance.

It added resistance manganese-copper non-induction regulation should be equal to external-connection resistance marked on scale board of movable ring gauge. Deviation error is ±0.1Ω.

5.2.2、热电阻作为测量元件：Taking RTD as measurement component:

在进行系统试验之前，应先查看温度显示仪表显示值应为该热电阻所在位置的环境温度，然后把电缆从热电阻接线端子拆下，接到标准电阻箱上，根据设备规格表要求分度量程，查对对应的温度对照表，

Prior to system test, firstly, observing carefully indicating value of temperature indication instrument shall be the situation temperature,which RTD was located. And then, dismounting cable from RTD connection terminal and connecting to standard resistance box, choosing corresponding division range according to equipment specification table, looking up corresponding temperature contrast table.

分别给出量程的三点上下行电阻值（50%测量点可选附近相对整数的电阻值），分别记录试验值，显示仪表试验误差值应符合要求。

Giving three-point up and down run resistance of range respectively (50% measurement point can select resistance near relative integer) and writing down test recorder. Test error of indicating instrument shall come up to requirement.

5.2.3、热电偶作为测量元件：

Considering thermocouple as measurement component:

在进行系统试验之前，应先查看温度显示单元显示值应为该测温点的环境温度然后把补偿导线从热偶接线端子上拆下，按正负接到mv发生器上，根据设备规格表要求分度量程，查对对应的mv对照表，分别给出量程的三点上下行mv值（50%测量点可选附近相对整数的mv值），记录试验值，显示仪表的试验误差值应符合要求。

Prior to test, firstly, cheking up indication value of temperature indication unit shall be the environment temperature of measured point, then, dismounting compensation lead-wire from thermocouple connection terminal, and connecting to mv generator in term of plus and minus. Selecting division range according to equipment specification table, looking up corresponding mv contrast table, sending out three-point up and down run values of range (50% measurement point may choose near relative integer mv valve) and recording test value. Test error of indicating instrument shall accord with requirement.

5.3、流量检测回路：

Flow detecting Loop:

5.3.1、常规流量计作为测量仪表：

Having general flow meter as measurement instrument:

试验之前，应首先确认流量计安装方向及前后直管段应符合要求，然后从流量计端子上拆下信号线，分别送出相应的电流或频率信号，记录试验值，显示仪表试验误差应符合要求。

Before test, verifying flow meter installing direction and front and back straight-pipe shall conform to requirement, then dismounting signal wire from the terminal of flow meter, sending out corresponding signal of current or frequency, and recording test result. Test error of indication instrument shall come up

to requirement.

5.3.2、用节流元件的差压式流量仪表（流量差压变送器）作为测量仪表：

Taking D/P flowing instrument (flowing D/P transmitter) as to be measured instrument:

把压力信号发生器连接到差变的正压室，负压室通大气，标准电流表串联到测量回路里，分别使压力信号发生器输出设备规格表要求量程的0%、25%、100%、100%、25%、0%，对应显示值应为流量量程的0%、50%、100%、100%、50%、0%，记录试验值，显示仪表试验误差应符合要求。

Connect pressure signal generator to transformer positive-pressure chamber, and negative pressure chamber to atmosphere. Make standard current meter connect in series to measurement loop. Let pressure signal generator output 0%, 25%, 100%. 100%, 25%, 0% of range according to equipment specification table, and corresponding indication shall be 0%, 50%, 100%, 100%, 50%, 0% of flowing range. Taking down test result. Error shall be within requirement.

5.3.3、带流量计算机的质量流量计作为测量仪表：

Keeping mass meter with flowing computer as measurement instrument:

先使流量计算机进行自检，通过后，从流量计算机里找到被测介质的粘度、密度、流量量程等参数应和规格书中相同，压力和温度补偿（如果有）显示值应符合当时情况，

After passing itself-inspection of flowing computer, find parameters such as viscosity, density, flowing range of medium to be measured from flowing computer and keep them the same as specification instruction. Indication of pressure and temperature compensation (if exist) shall be compliance with field condition.

给流量计算机置位分别输出三点上下行模拟信号，显示单元应有相应流量显示，记录试验值，最大误差应符合要求

Input three-point up and down going simulative signal to flowing computer separately, corresponding indication will appear and write down test result. The biggest error shall be compliance with requirement.

对于质量流量计，在开表前，应再进行一次零点校准。方法是：被测物科全部充满检测元件，没有气泡，然后通过流量计算机进行零点校准即可。

Zero point regulation shall be carried out again for mass flow meter before open the gauge. Method is: To be measured object is filled with checking elements, without bubble, then act zero-point calibration through flowing computer

5.4、物位检测回路：

Displacement detecting loop:

5.4.1、外浮筒液位计作为测量仪表：

Taking external pontoon level meter as measurement instrument:

在该系统中串联一标准电流表，根据被测介质的比重计算出用水校验时的测量范围（计算公式见单台仪表校准试验方案），在排污处加水分别给出三点上下行值，分别记录试验值，显示仪表的试验误差应符合要求。

Connect in series a standard ammeter into this system. According to density of being measured medium, calculate measurement range with water. (Calculation formula refers to test plan for single-instrument regulation.) Feed water at drainage outlet to give three-point up and down run value, and record test result. Test error of indicator shall meet with claim.

5.4.2、单双法兰液位变送器作为测量仪表，首先应根据液位仪表计算表查对该液位是否有迁移量，

For single or double flange level transmitter as measure instrument, checking the level meter whether has transference or not according to calculation table of level instrument.

如果没有，显示单元液位应指示为0（双法兰应把正负压室压力传导介质造成的压力差迁移掉），如果计算表中有迁移量，则显示单元液位应指示为零下；

level indicator is zero if not, (Removing off pressure-difference caused by pressure transmitting medium of positive and negative pressure chamber concerning double-flange) If existence of transference, level indication shall be under zero

然后把信号电缆从变送器端子拆下，接入mA发生器，分别送出三点上下行mA值，显示仪表试验误差应符合要求。

Then disconnect signal cable from transmitter terminal, connect into mA generator, and send out three-point up and down going mA value separately. Test error of indication instrument shall come up to requirement

如果是智能变送器作为测量仪表，在进行系统试验前，应在DCS系统调入智能变送器组态在线自检，检查该变送器位号、单位、量程及温度应符合要求，然后做修改参数试验。然后在现场用手持式通讯器强制变送器输出量程的0%、50%、100%、50%、0%并DCS检查其精度是否符合要求。

5.4.3、内浮筒、浮球、电容式、射频导纳、雷达、钢带、伺等料面液位计作为测量仪表。

Keeping material-face level gauge such as internal pontoon, floating ball, capacitor, radio-frequency, radar, steel strap etc. as measurement instrument.

料面液位计的系统试验应和甲方有关人员协商，如果可能，应由工艺专业人员配合向被测容器内加水（或别的允许的介质），进行零位和量程的标定，然后进行5点试验。

Carry out system test of material-surface level meter with

the cooperation of client relevant personnel if possible, feed water (or other permissive medium.) to measurement container with the cooperation of process special worker, mark zero-point and range, then do 5-point test.

如果不可能，应首先把信号电缆从液位计端子上拆下，直接用信号发生器加相应的模拟信号，误差应符合要求。然后在联动试车或化工投料试车阶段，用水或物料再做校准试验。

Disconnect signal cable from level meter terminal if impossible, and output corresponding simulative signal with signal generator. Error shall come up to requirement. Act calibration test with water or material during the linkage commission or chemical commence test-drive.

5.4.4、液位差压变送器作为测量仪表：

Having D/P level transmitter as measurement instrument .

该变送器可参考流量差压变送器进行系统试验。

Test the transmitter referring to D/P flow transmitter

5.5、成份检测系统：

Composition checking-up system；

在线分析仪表应按说明书要求，先通电恒温一定时间，按校验的程序要求通入样品，样气，进行零位及量程的标定，相应显示单元也应显示零位值及满量程值。

According to specification, energize and keep constant temperature to online analysis instrument for some time firstly. Inputting sample, sample gas, and marking zero-point and range. Corresponding zero-point value and full range value will appear in indication unit.

然后用mA发生器加mA信号，指示应为对应值，误差应符合要求。

After a while, input mA signal by mA generator, show will be right,

and, error shall be permissive.

5.6、报警系统试验：

Alarming system test:

5.6.1、检测系统的报警试验：

Alarming test of detecting system:

在进行检测系统报警试验时，在检测仪表（元件）处加信号至对应的闪光报警器及音响报警，记录报警值，然后按确认按钮，闪光报警器应变闪光为常光，音响应停止报警，再加信号至闪光报警器，闪光报警器应常光熄灭，记录报警解除值，报警误差值应符合要求。

When acting alarming test, pressurize signal from checking up instrument until corresponding flash alarm and acoustic alarm and write down alarming value. Then, press confirm-pushbutton, flash alarm shall turn flash into common light and acoustic shall stop alarming. Pressurize signal until normal light disappearance of flash alarm and take down alarm absolving value. Alarm error shall comply with requirement.

对DCS系统：在进行检测系统报警试验时，在检测仪表（元件）处加信号至对应的DCS点显示报警并记录报警值，然后按确认按钮，再加信号至对应的DCS点显示报警消除，记录报警解除值，报警误差值应符合要求。

5.6.2、压力开关作为为检测元件：

Taking pressure switch as detecting element:

用压力信号发生器给高报（低报）的压力开关缓慢加压（减压），至对应的闪光报警器及音响报警，记录报警值，然后按确认按钮，报警器应有相应动作。

Increase (reduce) pressure gradually to high alarm (low alarm) pressure switch with pressure signal generator up to corresponding flash alarm or acoustic alarming, and record alarming value. Then press confirm-pushbutton and alarm shall have corresponding action.

再减压（加压）至闪光报警器熄灭，记录报警解除值，报警误差应符合要求。

Reduce (increase) pressure up to flash alarm going out and record alarm-absolving value. Alarm error shall come up to requirement.

对DCS系统：用压力信号发生器给高报（低报）的压力开关缓慢加压（减压），至对应的DCS点显示报警记录报警值，然后按确认按钮。再减压（加压）至对应的DCS点消除报警，记录报警解除值，报警误差应符合要求。

5.6.3、温度开关、流量开关、液位开关作为检测报警元件：

Regard temperature switch, flow switch, level switch as detecting alarm element:

以上开关可采用人为短接或人为断开检查闪光报警器及报警音响的动作情况应符合要求。

Applying the above switches with man-made short-connection or breaking those switches in order to inspect flash alarm and alarming acoustic alarm which action shall be compliance with requirement.

对DCS系统：以上开关可采用人为短接或人为断开检查DCS对应的报警点动作应符合要求。

5.6.4、机械位置开关作为检测报警元件：

Taking machine position switch as alarming element:

机械量开关可以用手改变开关状态检查报警器动作情况应符合要求。

Inspect alarm action through manual changing switch condition. Action shall come up to requirement.

对DCS系统：机械量开关可以用手改变开关状态检查DCS报警动作情况应符合要求。

5.6.5、气体报警器报警系统：

Gas alarming system

按下报警试验按钮，仪表指针应指示报警值，断开任意一根连线，仪表应报警，然后用标准样气接触探头，仪表应报警，并指示相应含量。

Push alarming test pushbutton, pointer shall show alarming value. Instrument will alarm if disconnect any one wire. Then using standard sample gas to touch probe, instrument shall alarm and show corresponding content

对DCS 系统：在操作台上按下报警试验按钮，对应的DCS点应指示报警值，断开任意一根连线，对应的DCS点应报警，然后用标准样气接触探头，对应的DCS点应报警，并显示相应含量。

5.7、联锁保护系统试验：

Interlock protection system test:

5.7.1首先不投联锁，对所有的联锁条件和联锁结果分别试验。检查联锁动作值应符合要求，按钮、开关、电磁阀及向电气专业送的接点应动作灵敏、可靠。

Test all the interlock terms and interlock results separately without interlock system. Inspect interlock action shall comply with requirement. Action of pushbutton, switch, solenoid valve and the connection with electric equipment shall be sensitive and reliable.

5.7.2、由相关专业配合进行不带负荷的联锁试验。首先由相关专业人员确认负荷解除，联锁管道里没有物料，然后使联锁条件都处于正常状态，把联锁投上，按该联锁保护系统逻辑图，分别给出一定的条件，控制阀及控制机泵起动的接触器应相应动作。

Non-load interlock test should be carried out with the cooperation of relevant specialty. At first, verifying loading removal by relevant personnel and no material in interlock pipe. Then keep interlock terms normal and put interlock into use. Giving certain terms separately according to logic drawings of interlock protection system, control valve and contactor of pump starter shall

have corresponding action.

5.7.3、由相关专业配合进行带负荷的联锁保护试验。该项试验最好在单机试车的同时进行，联锁设备工作正常后，所有联锁条件都应处于正常状态，联锁投上，按该联锁保护系统逻辑图，人为给出一定的联锁条件，联锁设备应有相应的动作。

burden interlock protection test should be carried out with the cooperation of relevant personnel. The best time for test is at the same time of single commission. After interlock devices normally work, all interlock terms shall be normal. Putting interlock into use, in term of logic drawing for interlock protection system, giving artificially certain interlock term, devices shall have corresponding action.

5.8、调节系统试验：

Adjustment system test:

5.8.1、单回路调节系统试验（以DDZ-Ⅲ型调节器为例）：

Single-loop adjustment system test (take DDZ-Ⅲ type adjustor as example)

a、调节系统的测量部分按相应的检测系统试验进行。

Measurement parts of adjusting system shall be separately tested according to corresponding checking system.

b、把调节器的手动—自动开关切为硬手动，测量—校验开关置测量位置，用调节器的手动操作机构分别输出三点上下行值检查调节阀应有相应动作，调节器和调节阀的动作方向应符合要求。

Switch manual-auto switch of adjustor to hard manual, place measurement-regulation switch in to be checked location. Making manual operator of adjustor output three-point up and down going value. Control valve shall have corresponding action. Action direction of adjustor and control valve shall comply with

requirement

c、把手—自动开关置为软手动位置，把软手动操作键倾斜，调节阀应能全行程动作，当调节器输出一定值时，松开软手动开关时，调节器的输出应能保持，然后使软手动—自动、自动—软手动、硬手动—软手动—自动能实现无平衡无扰动切换。

Turn manual-auto switch into soft manual location, and make soft manual operating key incline. Control valve can act within full range. When adjustor output certain data, release soft- manual switch and output of adjustor can be preserved. Then, make soft manual-auto.、auto.-soft manual、hardmanual-softmanual-auto.

realize non-disturbance switch.

d、设定PID各参数为一定值，使测量针和给定针有一定偏差，则手—自动开关切为自动后，输出应按PID曲线变化。

Specify PID parameter a certain value and make measurement pointer and specified pointer have certain deviation. After manual-auto switch transfer to auto switch, output change shall comply with PID curve.

5.8.2、基地式调节系统：Base type adjustment system:

a、基地式调节器如为压力调节，应用压力信号发生器加压做检测试验，如为温度调节，调节器指示为测量点环境温度。

If base type adjustor is pressure adjustment, pressure signal generator shall be used to pressurize to checking experiment. If it is temperature adjustment, adjustor indication shall be condition temperature of measured place.

b、手—自动开关置为手动，用手动定值器输出三点上下行值，调节阀

应有相应动作。

Set manual-auto switch in manual position, output three-point up and down going value with manual adjustor, and control valve shall have corresponding action.

c、设定PID各参数为一定值，使测量针和给定针有一定偏差，投自动以后，输出应按PID曲线变化。

Specify PID parameter a certain value, keep measurement pointer and assigned pointer have some deviation. After

transferring to auto site, output shall comply with PID

curve.

5.8.3、复杂调节系统的试验：Test for complex adjustment system.

a、串级调节系统的试验：Series adjustment system test

上图为串级调节系统典型方块图

The above drawing is typical diamonds for series adjustment system.

①、串级调节系统试验应首先按单回路调节系统进行主（副）调节器的单独开环试验，主调节器的输出发生变化，副调节器的设定针（副调节器已改为外给定）应相应变化。

During test, doing single open-ring test of main adjustor according as single-loop adjustment system at first. When main adjustor output change, and specified pointer of vice-adjustor will change correspondingly. (Vice-adjustor has been turned into external assignment)

②、手—自动开关置为自动，使主调节器输出为一恒定值，改变副测

量参数，使副调节器测量与给定有一差值，则执行器应有相应变化。

Place manual-auto switch in auto location, and keep main adjustor output a constant value. Vary vice-measurement parameter, and make measurement of vice-adjustor and assignment exist a difference when actuator shall have corresponding change. ③、使副测量参数保持一恒定值，置主调节器手—自动开关切为自动，改变主测量参数值，使主调节器测量针与设定针有一定差值，则执行器应有相应变化。

Keep vice-measurement parameter preserve a constant value, shift manual-auto switch of main adjustor to auto. Vary main

measurement parameter, exist a difference between main adjustor measurement pointer and specified pointer, so, actuator shall have corresponding shift.

b、比值调节系统（以单闭环比值调节系统为例，采用乘法器）：

Ratio test system (take single closed-ring ratio test system as example, applying multiplier)

上图为单闭环比值调节系统的典型方块图

.