There are a variety of single-phase sockets, often divided into two holes and three holes.
The two holes are arranged side by side, and the three holes are formed in a shape of a character.
The letter next to the wiring hole, L is the fire N is zero.
There is also E in the three holes, indicating that the ground is in the middle.
In the direction of the socket, the wiring of each hole is specified.
The left connected zero line is connected to the right and the protective ground line is connected to the center.
Leakage protector selectionSelect the leakage protector and the power supply mode is first.
Single-phase power supply 220, second-line secondary or single-stage.
Three-phase three-wire three-eighth, three-level protector is selected.
Three-phase four-wire three-eighth, four-wire three-level or four-level.
"Level" means that the switch contact "line" indicates the incoming and outgoing lines.
Core inspection and breakpoint determination method before buried conductor is buriedBefore the buried conductor is buried, there is no broken core disc inspection.
Check that the meter is used, and the L end is connected to the wire.
The other end of the wire is placed in the water.
Slowly shake the megohmmeter, the needle is less than zero is broken.
Find where the breakpoint is, use the instrument DG3,
One-phase AC is connected to one end, and the instrument is buried in the ground.
Slowly moving from head to tail, the lamp light is not broken,
If the instrument light is off, here is the disconnection point.
Method for judging AC single-phase circuit fault by low-voltage electroscopeThe electric pen for AC electroscope is lit, and the fire line is not bright.
Circuit failures can be checked and energized to measure fire and ground.
When the device is turned on and off, the circuit is disconnected and unquestionable.
If both ends are not lit, the power line is disconnected.
If both ends are bright, the zero line breaks or detaches.
Method for measuring conductor DC resistance by pointer multimeterMeasure the resistance selection range, select the range and then zero.
Two shorts to see the hands, not to adjust at zero.
Rotate the ohms zero button and the hand is zero.
There are still a number of knobs, and the battery is replaced and adjusted.
The contact must be good, and the two hands should be suspended.
The measured values ​​are guaranteed to be accurate and the hands are preferably in the grid.
Turn off the power after measuring, and turn the knob to the voltage.
Weight estimate per kilometer of wireThere are multiple kilometers of wire, depending on the section and variety,
The section is in millimeters and is multiplied by the coefficient value.
The hard aluminum is the lightest at 2.8%, and the pure aluminum is the third.
The steel core aluminum strand is multiplied by four, and the seven-eighth-eight iron is relatively heavy.
Then re-pure copper is 8.8%, and the steel strand is the most heavy at 9.0.
Consider the sag and lashing, then multiply the zero and three times.
Correlation formula: mass = density X volume
Volume = bottom area X height
Judging the quality of capacitors by charging and discharging
Capacitor is good or bad, and the charge and discharge method can be assumed.
The capacitor is connected to DC at both ends, and it will be cut off in a few moments.
The conductor is connected to two poles, and there is no spark to watch.
There is fire for good and no fire, and the same kind of fire is fuller.
Calculation of total resistance after series connection and parallel connectionThe series resistance of the resistor increases, and the longer the string, the longer the resistance.
The parallel value of the resistor is reduced and the equivalent cross section is increasing.
Parallel total resistance is more difficult to find, and each value first requires a reciprocal.
The reciprocal of the sum of the reciprocals is the resistance after paralleling.
There are only two resistors in parallel, and the total resistance can be obtained by simple method.
The product of the two resistances is the numerator, and the sum of the two resistances is used as the denominator.
The outer layer of double wall heat shrinkable casing is made of high quality polyolefin alloy and the inner layer is made of hot melt adhesive. After molding, the product is crosslinked and continuously expanded by electron accelerator irradiation.
The outer layer has the advantages of softness, low temperature shrinkage, insulation, anti-corrosion and wear resistance, while the inner layer has the advantages of low melting point, good adhesion, waterproof sealing and mechanical strain buffering.
Widely used in electronic equipment wiring waterproof, leakproof, multi-strand wire harness sealing waterproof (such as home appliance wiring harness, automotive wiring harness, etc.), wire and cable branch sealing waterproof, metal pipeline corrosion protection, wire and cable repair, water pump and submersible pump wiring waterproof and other occasions.
Double wall heat shrinkable casing is produced by double layer co-extrusion process of polyolefin halogen-free flame retardant material and hot melt adhesive.
The outer layer is polyolefin, which has the characteristics of insulation, halogen-free flame retardant and low temperature shrinkage. The inner layer of hot melt adhesive has the advantages of low melting point, good adhesion, waterproof sealing and mechanical strain buffer.
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