The four major instrument and control system fault diagnosis plan, electrical fault diagnostics, encyclopedia, electrical engineer construction 98 ports, electrician's 109 practical ports, dry goods 100%, first collection!
1
Temperature meter failure judgment step
Fault phenomenon:
The temperature indication is abnormal, high or low, or changes slowly or even not change.
Take the thermal resistance as an example. First of all, we must understand the process conditions, ask the technicians about the condition of the measured medium, whether it is a normal medium or a test medium such as water, and whether it is a normal working condition. If it is not a newly installed thermal resistor, the possibility of reversing the polarity of the line can be ruled out. After excluding the above reasons, judge and check according to the diagram.
Temperature detection failure judgment (Y indicates yes; N indicates no)
2
Pressure detection failure judgment
Fault phenomenon:
A pump outlet is not normal, high or low, or zero or no change.
Take the electric pressure transmitter as an example (3051C). First of all, it should be understood whether the measured medium is gas or liquid. Understand the process driving conditions and the simple process flow. According to the understanding of the process conditions and instrument fault phenomenon to determine the instrument fault and processing.
The fault diagnosis and processing can be checked according to the diagram.
3
Flow detection failure judgment
Fault phenomenon:
The flow indication is abnormal, high or low, or indicates zero, indicating fluctuations.
Take the differential pressure flow transmitter as an example (orifice flow meter) When the instrument maintainer is dealing with a fault, he should understand the situation from the process operator and understand the process conditions, such as the condition of the measured medium, the pump condition, and the process flow.
Through a detailed understanding of the process driving situation, the fault handling can be judged and checked according to the ideas shown in the figure.
4
Level detection failure judgment
Fault phenomenon:
Level indication does not change, high or low, or no indication.
Dual flange level transmitters are used as test instruments. First of all, we must understand the process conditions, process media, the object being measured is the original stable tower, or tank (tank), reactor.
The use of dual flange liquid level transmitter to measure the liquid level, often at the same time configure the local display level gauge, the process operator to local level gauge as a reference to determine the differential pressure liquid level transmitter measured value indicated high Or it is low because it is more intuitive to display the level gauge on the spot.
The instrument maintenance personnel should judge and check according to the process conditions and instrument fault phenomena.
About the level (level) detection failure to determine the idea can refer to the map.
5
Control system failure judgment
Fault phenomenon:
The control system is unstable and the input signal fluctuates.
Taking a simple flow control system as an example, the control system consists of a double-flange liquid level transmitter, a single loop regulator, and a pneumatic diaphragm control valve with an electric valve positioner.
In dealing with such failures, the instrument maintenance personnel should be very clear about the composition of the flow control system, to understand the process conditions, such as process media, simple process flow, is the feed flow or discharge flow or tower flow back. See the troubleshooting procedure for details.
6
Electrical fault diagnosis
Sensory diagnosis is quick and easy
1. Judgment of abnormal sound of power transformer
Run a normal transformer and make it clear and even.
There is abnormal sound in the distribution transformer and the cause of the fault is judged.
The buzzing tone is high, overloaded or over voltage.
Intermittent and violent rattles, single-phase load increases sharply.
When the hammering sounds, the piercing screw has loosened.
The applause sounded and the ground wire broke.
Intermittent squeaks and poor grounding.
Winding short circuit is relatively minor, issued bursts of buzz.
The windings are short circuited and emit a loud roar.
The high-voltage casing is cracked and emits high-frequency buzz.
The high-voltage lead shell flashes, cracking sound.
The low-voltage phase line is grounded, and the old one hears a loud roar.
Drop switch tap, poor contact sound.
2, using semiconductor radios to detect partial discharge of electrical equipment
Inspection and distribution equipment, partial discharge is difficult to find.
Bring a pocket radio, tune to no radio station.
The volume is louder and louder, and the sound is even.
If the sound is irregular, there is a loud sound of firecrackers.
Or there is a loud buzzing sound and partial discharge nearby.
Then turn down the volume and measure it closer to the device.
The complex heard another sound of firecrackers and the equipment under test was malfunctioning.
The device is partially discharged and emits high-frequency electromagnetic waves.
3, use the sound bar to diagnose the motor common fault
Use the listening stick to listen to the actual motor fault.
Hearing continued buzz, the rotor rubbed against the stator.
The speed becomes slower and the coil touches the shell.
The speed becomes slower and the coil breaks one phase.
The bearing chamber is buzzing and the bearing lubricant dries.
The bearing part rattled and it was determined that the bearing was damaged.
4, check the wood shaft hollow hitting method
Inspect the wooden poles and tap around the shaft.
When the sound is crisp, the buzzing sounds hollow.
5. Inspect the insulation condition of the generator set bearing with insulated conductors
When the generator set is running, the bearing insulation can be used to inspect it.
The head is stripped of the insulated wire, and the wire is grounded first.
At the other end, touch the rotary shaft and carefully touch it several times.
Spark insulation is poor, good insulation without sparks.
6. Judgment of single-phase ground fault in neutral ungrounded system
The three-phase voltage is the largest, and the lower phase must be faulty.
7, inspection inspection power capacitors
Inspection of the capacitor, bulging oil temperature rise.
The humming sound is abnormal and there is a discharge failure inside.
8, determine the quality of small capacitors using charge and discharge method
Small capacitor is good or bad, charge and discharge method rough judgment.
Both ends of the capacitor are connected to the power supply and charge for about one minute.
With insulated copper wire, short the two electrodes of the capacitor.
Sparkling sparks are good, no sparks are damaged.
9, identify the polarity of lead batteries
Lead-acid batteries have two polarities. The positive and negative signs are not clear.
The color of the poles is different, and the cathode ash is dark brown.
The position of the pole is different, relying on the positive side of the factory sign.
The diameter of the pole is different, and the anode is thinner than the cathode.
The saw blade is broken and the positive electrode is harder.
The pole lead is inserted into the sweet potato, and the line turns green to be positive.
Connect the two conductors of the pole, immersed in dilute sulfuric acid solution,
Bubble end negative electrode, no bubble end positive electrode.
10, scraping fire to check whether the battery cell battery short circuit
The internal short circuit of the battery occurs in one or two compartments.
Single-cell battery short circuit, commonly used scraping fire inspection.
With a thicker copper wire, connect a single cell,
Hand the other end of the copper wire and wipe the other pole quickly.
Blue and white sparks appear, and the single cell tested is in good condition.
Red sparks are power shortages, and no sparks have short circuits.
11, pumping the phase voltage method to check the two components three-phase energy meter wiring
Three-phase three-wire energy meter, pumping phase voltage check.
With the load constant, disconnect the neutral phase voltage line.
Watching the operation of the electric meter, the disc is halfway down,
The only correct connection, otherwise the wiring is wrong.
12, to determine whether the line inside the micro-meter table is broken
The micro-ampere coil is off and the multimeter cannot measure it.
After the micro-ampere meter terminal, the green wire is shorted,
Then shake the microampere meter while looking at the meter pointer.
The slow swing is small and the coils in the watch are intact.
Swings faster and faster, and the coil in the watch is broken.
13. Analyze and judge the fault according to the fuse blowing status
Look at the fuse blowing condition to determine the fault within the line.
Exposed fuses are fully fused, severely overloaded or short-circuited.
Fracture in the middle of the fuse is small and the normal overload time is long.
Near the crimping screw, the mounting damage is not compressed.
14, according to the color ring logo to identify the size of the resistor
Finished small resistors, color ring nominal resistance value.
The first ring of color circle is determined, close to the edge ring of the resistor.
The last loop is the deviation, and the second loop is the multiple.
The remaining color ring resistance rings indicate the effective number of resistance values.
The color of the color scale represents the number, times the power of tens of thousands.
Brown, orange, yellow, green, blue, purple, 12345,
Eighty-nine white and black are zero, gold and silver are two negative multiples.
15, poor quality aluminum core insulated wire identification method
Plastic insulated aluminum core wire, see the quality of the core.
The core is soft and silvery white, and the inferior color is harder.
Skin color Yan factory name, poor old no logo.
The outer core wire is tightly contacted, and the inferior core is made of Komatsu.
16, identify incandescent bulbs
Incandescent light bulbs are good or bad, see the hand mold to identify.
The bubble is bright and smooth without blisters, and the product logo is printed clear.
The glass wick is not skewed and the wire hooks are arranged in a row.
The installation of the lamp holder is not skewed, and it is not felt to be pulled hard.
17, identify the quality of transformer oil
Looking outside the transformer oil, the new oil is usually light yellow.
Light red after operation, darkening of oil aging
Different intensity of different colors, carbonized serious color black.
The oil in the test tube looks bright and the oil is transparent and fluorescent.
There is no blue-violet reflection, and there is a difference in transparency.
Good transformer oil is odorless or has a bit of kerosene.
Dry overheated coke odor, serious aging sour.
When an arc is generated in the oil, it smells of acetylene.
18, drip detection motor temperature rise
The temperature rise of the motor drip test, sprinkle a few drops of water on the case.
There was only no heat and no sound. The measured motor was not overheated.
When the steam blows, the motor overheats.
19. Simple method for judging steering before installing three-phase motor without rotor
Motor steering prediction, rotor not installed.
The copper wire is bent into a barrel shape, and the inner diameter of the stator is determined by the barrel diameter.
The stator is fixed vertically and the cotton bucket is placed in it.
After the barrel is stopped, it is energized instantaneously and the bucket rotates steadily.
20, the motor insulation mechanical strength four criteria
Motor insulation strength, mechanical strength to measure.
Sensory diagnosis finger press, four-level criteria.
There is no crack on the finger and the insulation is hard to feel.
A small crack occurred on time and the insulation was in a fragile state.
A large deformation occurred on time and the insulation was badly stopped.
21, touch temperature method to detect motor temperature rise
Motor operating temperature, hand temperature method to detect.
Feel the finger does not feel hot, flat on the back of the shell.
The hand touched red for a long time, and it was slightly hot for about fifty degrees.
The hand can stay for two or three seconds, and sixty-five degrees is very hot.
The hands were very hot after touching, and it was extremely hot at 75 degrees.
The hands barely touched and 85 degrees were overheated.
22, hand mold low-voltage fuse insulation location of the insulation temperature fuse which phase melting
On the low voltage distribution panel, multiple fuses are arranged.
Hand-molded tube insulation, hot-melt melt.
23, hand-pull wire method to find the fault between the soft-core break point
Single-core rubber sheathed soft wire, intermittent core search method.
Hold the outer skin with both hands, separated by more than 200 millimeters.
At the same time, pull it hard and check it carefully.
When the wire diameter suddenly becomes thinner, it is the breakage point.
7
Electrical engineer builds 98 recipes
Foreman request
The chief electrician please note that the construction procedures should be kept in mind.
Based on the design drawings, seriously look at the problem.
Cross-construction changes frequently, and standard specifications must be memorized.
Before the construction is completed, the material plan should be mentioned earlier.
Civilized construction ranks first and safety production ranks first.
Technical measures are effective and quality assurance systems are in place.
The model practice should be promoted and implemented according to quality management.
Advanced science and technology should be adopted and operations should use new processes.
Material equipment first check, record form fill in detail.
Products must have a certificate, inspection certificate must be prepared.
Construction preparation
There are many items for the preparation. The details are listed below.
Power Distribution Box, high voltage distribution cabinet.
Wire and cable hard bus, large lamps and lightning protection.
Circuit breakers and transformers, various types of mutual inductance and motors.
Operating mechanism and instrument, emergency power capacitor.
Do not forget the transformer oil, the battery with sulfuric acid solution.
Pipes and wires are checked, and cement poles are included.
Attachment materials should be qualified and various accessories should be available.
Install holes to stay early and position elevations to be accurate
Beam column wall and roof, decorative surface and box mouth.
Concave and convex phenomenon to overcome, concave two centimeters to repair.
The surrounding blockage must be tight and it must not be hollowed out.
Electric pipe laying
The buried pipeline must be protected and the pipe should be centered on the wall.
The buried pipe must be rust-removed and the interior walls should be painted with anti-corrosion paint.
The line pipe reinforcement should be tied, and the main reinforcement and pipe welding are not allowed.
The tubules should be connected with threaded fasteners. Butt welding can also be used.
More than seventy clear pipes allow the use of casing welding.
The nozzle is aligned with the center of the sleeve, and the length of the sleeve should be standard.
Two times the outer diameter of the tube, thin tube welding must not be allowed.
The pipe hoop is connected to the ground, and each end must be welded on both sides.
Ground diameter according to regulations, flat steel welding to three sides.
The welding length of flat steel is twice as wide, and the length of pipe welding is six.
The main reinforcement is used as a lightning conductor, and the lead is to be welded.
The ground resistance is measured first, and the hidden inspection is complete.
Zero protection to power supply, protection ground box box.
The wall thickness is less than two millimeters and the ground wire crimping point is not used.
Line tube in and out of the box, the use of silk lock bus.
The dark tube is put into the box and it should be spot welded around.
Spot welding is only done three or five times. The weld joint is painted twice.
Exchanges are less than 50 volts, and dc is the limit.
It is a safe voltage block and piping is not used for jumper wiring.
Fire button junction box, behind the dark box wall.
The pre-embedded work is over and the ground connection is complete.
The end of the process to do covert, timely inspection and acceptance.
The hidden content is divided into five points and the project parts are written thoroughly.
The zone is connected to the grounding electrode and the structure is embedded with a wire tube.
Can not enter the ceiling, hidden to do laying pipe.
The main ribs are connected for lightning protection, and the hidden resistance is measured first.
Directly buried cables should be missing, and the specifications should be filled together.
The details of the record are detailed and cannot be dealt with.
The three parties accepted the signature and saved the data into the file.
Changes in the project to negotiate business, the difficulty is to find a design institute.
Offline installation
With more than half of the engineering works, installation and threading are conditional.
The structural engineering has been verified and the brick and tile decoration has been initially completed.
Finished product protection is guaranteed and the pipe is dry and insulated.
All construction is good, the color of the wire should be clearly distinguished.
The color of the trunk line can be divided, and the box branch road should be obvious.
The zero line should be light blue and the phase line should be yellow, green and red.
Green yellow PE ground wire, can not be randomly selected.
All parts of the pipeline are concealed and tightly connected.
Conductors must not be exposed, and the box cover must be closed.
Rat fire can not be smashed, and safe power supply is guaranteed.
The wire connection is stipulated, and welding and winding cannot be performed.
Pressure line hat spiral button, single strand aluminum wire should be used.
The line and nose section must be consistent, and the copper and aluminum connections must be transitional.
The inner wiring is bundled into a bundle, and the inside of the box is connected.
Clean, tidy, and free from contamination.
The board shutters should be grounded, and the grounding zero line should be obvious.
The single-phase socket speaks of safety, left-right zero fire on the ground.
The three phases below form a triangle. The ground hole is larger than the top.
After the lighting switch is installed, the horizontal and vertical are beautiful.
Finished installations are done in order and each process is pre-inspected.
Inspection and acceptance
Clear distribution pipelines should be pre-inspected, and the compilation includes seven aspects.
Variety specifications and elevation, fixed position and appearance.
Anti-corrosion treatment does not fall off, including the ceiling internal pipe.
Pre-inspection with the process to do, check there are aspects.
Change the device power cord, lamp switch and cable.
Strong and weak sockets should have, slot trays and trays.
The direction of the power outlet is accurate, and the position of the equipment cannot be biased.
The installation dimensions are consistent and the inspectors will be named.
Each procedure should be summarized, and the team should examine and check each other.
The quality assessment must be synchronized and the content must be completed.
Guarantee the project to ensure that the basic project should be sampled.
Measurement items to be measured, the various points marked.
Timely summary evaluation, unity and quality control.
After the conductor passes the test insulation, carefully record and wait.
Equipment power and lighting, the main branch line to complete.
System lightning protection and protection, working ground anti-static.
All four types of grounding should be done.
After the installation work is done, then run the test.
Self-controlled motor with heating, signal sound and antenna.
TV and telephone, monitoring storage and power generation.
After a single transfer of the comprehensive test, the trial run records are all available.
Do not forget the high-rise building, full load test.
There is a limit to the trial run time, see Regulations and Specifications.
After the commissioning process is completed, the quality assessment is finalized.
At the end of the work to do the chart, change the contact details.
Carefully plan and check, the quality of the project is not difficult.
8
109 practical tips for electricians
Electrician's mouth (1)
Easy estimation of wire carrying capacity
Ten out of five, one hundred two, twenty-five thirty-five, seven and ninety-five times more than half, temperature 80% off, copper upgrade count.
Electrical technicians (2)
Known transformer capacity, find its rated voltage rating side
Description: Suitable for any voltage level.
Mouth: The capacity is divided by the voltage value, and the quotient is divided by six by ten.
Electrician's mouth (3)
Roughly check the accuracy of low-voltage single-phase energy meter
Hundreds of bulbs are connected one at a time and the switch is closed again.
Simultaneously count the number of revolutions and record the hexadecimal revolution value.
One of the meter's dials is the number of kilowatt hours of disk rotation.
The value is reduced by a factor of 100 and is roughly equal to the number of records.
Electrician's mouth (4)
Known three-phase motor capacity, find its rated current
诀 诀 诀 诀 诀 诀 诀 诀 诀 诀 诀 诀 诀 诀 诀 诀 诀.
Electrician's mouth (5)
Measure the secondary current of the power transformer and calculate the load capacity
Knowing the secondary pressure of distribution transformer, the current is measured in kilowatts.
The voltage level is four hundred volts, and one Amp is six kilowatts.
The voltage level is 3,000 volts, and an ampere is 4.5 kilowatts.
The voltage level is 6,000 volts, and an ampere is 9 kilowatts.
The voltage level is ten kilovolts, one for one and one fifteen kilowatts.
The voltage level is thirty-five thousand, one and fifty-five kilowatts.
Electrician's mouth (6)
Known small 380V three-phase cage motor capacity, seeking the minimum capacity of its power supply equipment, load switch, protection of the melt current value
Direct starter motor, capacity does not exceed ten kilowatts;
Six times kW selection switch, five times kW with melt.
Power supply equipment KVA requires three times the kilowatts.
Electrical technicians (7)
Measure the no-load current of nameplate 380V single-phase welding transformer and calculate its rated capacity
诀 : 380 welding capacity, no-load current multiplied by five.
Electrical technicians (eight)
Judging alternating current and direct current
Electric pens judge AC and DC, AC bright DC dark,
The exchange tube is bright and the DC tube is bright.
Electrical technicians (9)
Using electric pens for low voltage nuclear phase
Judging that the two lines are the same, each holding a pen,
The two legs are insulated from the earth, and each of the two touches a thread.
Look at a pen with your eye, not bright and different light.
Electrical technicians (ten)
Cleverly using electric pen to judge positive and negative DC current
Electric pen to determine the positive and negative electrodes, observe the fistula to be careful,
The front end is bright and the rear end is bright.
Electrical Engineer (11)
Using electric pen to judge whether the DC power supply is grounded or not, and the difference between positive and negative grounding
DC coefficient of substations, electric pen touch does not shine;
If it is near the tip of the pen, there is a ground fault at the positive pole;
If it is close to the finger, the ground fault is at the negative pole.
Electrician's mouth (12)
Using electric pen to judge phase-to-earth fault of 380/220V three-phase three-wire power supply line
Star connection three-phase line, electric pen touch two bright,
The remaining one is weak, and the phase conductor is grounded;
If it is hardly visible, the metal is grounded.
Electrician's mouth (13)
Wiring for motor wiring
Mouth: 2.5 plus 3, 4 plus 4; 6 plus 6, 25 5; 120 leads, with a hundred
Electrician (14)
Calculate current by power
诀 诀:
Electricity is doubled and electricity is added half.
Single-phase kilowatts, 4.5 amps.
Single phase 380, current two and a half.
Electrician's mouth (15) Conductor resistivity
Conductor material resistivity, ohms square per meter, length 1 meter, cross-sectional area of ​​1 square millimeter conductor resistance, temperature in Celsius 20,
Copper, aluminum, iron and carbon are ranked in order and do not need to be smashed. To increase the number of times to count, the smallest of 175 copper, the value of 233 aluminum, a full number of pure iron, carbon value is the largest, a full 100 million no fraction.
Electrician (16)
Direction of magnetic field and direction of current generated by powered straight wire and solenoid
The conductor conducts a magnetic field, and the right hand judges its direction.
Hold the straight wire in your hand and point your thumb in the flow direction.
The four fingers are held in a circle and the fingertip points in the magnetic direction.
Energized wire solenoid, forming a magnetic field north and south,
Antarctic S Arctic N, making judgments is very simple,
The right hand holds the solenoid and the current direction is four fingers.
Refers to the end of the N pole, you said convenience is not convenient.
Electrical Engineers (17)
Impedance, reactance, inductive reactance, capacitive reactance
Inductor impedance is called inductive reactance, capacitive resistance is capacitive reactance,
Inductance, capacitance in series, inductive reactance, capacitive reactance,
Resistance, inductance, and capacitance are connected in series, and resistance and impedance are combined.
Each of the three sides is a side, which is followed by a hook, a strand and a chord.
The Pythagorean theorem can be used, and it is known that both sides seek one side.
Electrical Engineer (18)
Capacitance series parallel calculation
The series value of the capacitor drops, and the length of the board is increasing.
The sum of the contents is summed again, and then the total capacity is counted down.
The parallel value of capacitance increases, and the board is increasing.
And after the capacity is very good, the capacitance values ​​to add.
Recall that the resistors are connected in parallel and the capacitance calculation is the opposite.
Capacitor series resistance, capacitor parallel resistance string.
Electricians (19)
Phase relationship between current and voltage in inductive load circuit
When the power supply is turned on, the current is difficult to reach.
Cut off the power supply voltage, the current is difficult to cut off,
The above metaphor is more popular and the voltage is before it.
The difference between the two electrical angle, the maximum value of ninety degrees.
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