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Electrical Troubleshooting
Electrical troubleshooting involves checking and resolving an electrical problem (such as when an electrical device stops working correctly). Common troubleshooting practices include checking if the power is on, the bulb has burnt out, or the breaker tripped.
885 Questions
What is an indication that an inadequate power supply is the source of an intermittent problem?
the power supply whines when you first turn on the system
What does the points X N L1 and L2 mean in the defrost timer?
In electrical terms X usually refers to a transformer's secondary terminal output. Example X1, X2, X3, and X4. If the timer is a clock defrost timer then the X represents a point where the timer release relay connects to.The letter N represents the neutral conductor. On controls it should be a white wire.
L1 represents a line conductor which means a "hot" wire. From L1 to N the voltage applied should be 120 volts.
L2 is a second line conductor, the voltage applied across L1 to L2 should be 240 volts.
What is the telltale factor for ascertaining where faults in a cable lie?
Impedance.
Depending on the cable type, it may also be possible to use a device called a "reflectometer", which sends a pulse down the wire and calculates the distance based on how long it takes for the signal to bounce back. This type of device works best for coaxial type cable.
What does it mean when Back light on lancer is out?
MOST LIKELY...
when a dashboard back light is out it's usually caused by one or more burned out bulbs.
What is cos on an electric motor?
Cos phi is a European term used on a motor to differentiate between apparent power (kVA) of an inductive load as compared to the active power (kW) that is really used by the load. Cos phi= active power/apparent power.
In North America a more familiar term would be power factor. Power factor = kW/kVA
First, check the nameplate on the motor. The FLA or full load amperage is the required start up current and is typically 125-150 % higher than the running load amperage (RLA). So a current draw of 39.5 while starting would be normal for a motor drawing 25 A in run mode.
You don't need any calculations. If the stated RLA is close to 25 A and you're drawing 25 A then the motor is fine. As long as you're supplying the correct full voltage required by the motor, it will operate at "full capacity". There are numerous formulas for motors. I would need to know the motor's horsepower, voltage, whether it's single or three phase and its stated efficiency (EFF on the nameplate), the FLA and RLA to tell you if the motor is running properly or if it's going bad.
How do you calculate current in Star Delta for 10kw 3phase 415 volts induction Electrical Motor?
Since watts = volts times amps times 1.73 times power factor (for a three phase motor): W = E * I * 1.73 * PF Solving for I: I = W / (E * 1.73 * PF) Lets say your motor has a PF of 0.85: I = 10000 / (415 * 1.73 * 0.85) I = 16.39A If this is for your homework (I hope not) and PF is not given, then you will substitute 1.0 for the PF and, of course, arrive at a different answer!
Use of symmetrical component in fault studies?
Symmetrical components are used to model faults on unbalanced high-voltage transmission/distribution systems, in order to predict the magnitude of fault currents resulting from various types of short-circuit fault, so that appropriate settings can then be applied to protective systems.
The basic principle behind the method of symmetrical components is that any unbalanced three-phase phasor diagram can be represented by three balanced phasor diagrams, called 'symmetrical components', termed:
- positive phase-sequence diagram (displaced by 120o)
- negative phase-sequence diagram (displaced by 120o)
- zero phase-sequence diagram (in phase)
This enables the electrical system to be represented by three sets of balanced phasor diagrams, rather than by a (terribly complicated!) unbalanced phasor diagram. This, in turn, allows the line fault impedances to be calculated relatively simply -these are represented by Z1, Z2, and Z0 -where Z0 represents an impedance path associated with earth faults.
Further explanation of this topic is well beyond the scope of this answer, and an appropriate textbook should be consulted.
Can a 130W fan be installed into a 120V outlet?
Yes, a 130 watt fan can be plugged into a 120 volt receptacle. The current draw will be I = W/E, Amps = Watts/Volts = 130/120 = 1.08 amps.
Separate source transformer testing?
During maintenance following test to be done :
transformer oil test
ht / lv side insulation test also hv to lt
oil temperature trip / alarm
winding temperature trip / alarm
bukkhoze relay trip / alarm
PRV setting to ok
MOG trip / alarm etc.
What is the minimum acceptable reading for magger test for 480v motor?
if check voltage is 2000v then acceptable range is 400
What will happen if electricity turned off for two weeks?
The effects of not having electricity for a few weeks depends largely on the weather. In a humid climate during the rainy season, you may find that the drywall becomes damp and, later, mold may develop. When the air conditioner comes back on, it may take awhile to dry out the home and to get the walls cool again. In a dry winter, your ceiling and other weight bearing walls may develop cracks as the wood contracts. Also, you should winterize and drain your pipes so they do not freeze and burst. Your appliances should be fine; however, if the lack of electricity causes your freezer foods to defrost without any ice crystals, you should empty and clean out the freezer and refrigerator. Wash them out and block the doors so they stay open.
Why it is necessary to have a back up power generator for a supercomputer?
There are two ways to run with this;
- Depending on the size of the "supercomputer" I would think that it would have its own designated UPS
- A "power generator " would be of little use, because by the time it had kicked in, you would be in dire trouble.
If I was installing a server room and a client asked me as part of the Project can you install something that will save my data in the event of power failure, I would advise a UPS.
The size of the UPS would depend on the size of the computer to be protected.
Why doesn't a shunt motor operate on a single phase AC supply?
Shunt motors do operate on single phase AC. There are millions, if not billions of them worldwide running right now.
Make certain your voltage supply is correct for your motor. Also, make certain you're providing the proper amperage. Make sure it's not a three phase motor. (three phase motors won't operate on single phase power.) If your supply voltage and amp supply is correct and the motor still doesn't run, you've got a bad motor.
What happens if you change over too soon from star to delta?
The Star/Delta starter was probably the most commonly used reduced-voltage starter, but in a large number of applications, the performance achieved is less than ideal, and in some cases, the damage and interference is much worse than that caused by a Direct On Line starter.
Electronic motor-control systems, which offer soft-starts in DELTA configuration, are now replacing the use of manual or semi-automatic star-delta starters.
The Star/Delta starter requires a six terminal motor that is normally delta-connected direct to the 3-phase service lines. The Star Delta starter employs three contactors to initially start the motor in a star connection, then after a period of time, to reconnect the motor to the supply in a delta connection.
If there is insufficient torque available while connected in star, the motor can only accelerate to partial speed. When the timer operates (set normally from 5-10 seconds), the motor is disconnected from the supply and then reconnected in Delta resulting in full voltage start currents and torque.
The transition from star connection to delta connection requires that the current flow through the motor is interrupted. This is termed "Open Transition Switching" and with an induction motor operating at partial speed (or full load speed), there is a large current and torque transient produced at the point of reconnection. This transient is far worse than any produced by the DOL starter and can cause severe damage to equipment and the supply.
If there is insufficient torque produced by the motor in star, there is no way to accelerate the load to full speed without switching to delta and causing those severe current and torque transients. These must be allowed-for in the design of the motor and its starting system if they are to have an economic useful life.
Technical explanation
When the windings of a 3-phase motor are connected in STAR:
- the voltage applied to each winding is reduced to only (1 /.'/'3) [1 divided by root three] of the voltage applied to the winding when it is connected directly across two incoming power service line phases in DELTA.
- the current per winding is reduced to only (1 /.'/'3) [1 divided by root three] of the normal running current taken when it is connected in DELTA.
- so, because of the power law V [in volts] x I [in amps] = P [in watts],
the total output power when the motor is connected in STAR is:
PS = (1 /.'/'3 VL) x (1 /.'/'3 ID) = 1/3 [one third] PD
where VL is the phase line voltage
ID is the line current drawn in DELTA
PS is the total power the motor can produce when running in STAR
PD is the total power it can produce when running in DELTA.
- a further disadvantage when the motor is connected in STAR is that its total output torque is only 1/3 of the total torque it can produce when running in DELTA.
For more information please see the answers to the Related Questions shown below.
What is the SI unit for direct current?
The SI unit of EMF (electromotive force) in a direct current circuit is Volts. The circuits current is measured in ampere's
Can you get both 12 and 24 volts from 2 - 12 volt batteries?
You will need a second battery in series with the first battery to produce the 24 volts DC. To keep it charged the series connection will have to be manually changed to a parallel connection.
The part of the circuit that is tied to a ground rod that is usually 6-8 ft long and is driven in the actual ground outside a building. Most local electrical codes require the ground circuit also be tied to the neutral bar in the electrical service panel. Effectively, you are causing the neutral bar to be grounded electrically to physical earth ground.
A ground circuit can also be on a vehicle. It usually is the car body and chassis used as a return path for electrical currents back to the battery negative post. Some vehicles use a positive ground instead of a negative ground (European vehicles usually).
What reading will be displayed on a DVOM if the scale is exceeded?
It depends on the device and manufacturer, but most digital multimeters will display "OL", which indicates an OverLoaded input for the specified range. The term "overload" doesn't necessarily mean that a voltage or current is necessarily at a dangerous level or a level that might damage the device, but rather that the upper limit of its measuring capability has been reached.
In order to protect the equipment from damage, it's a good idea to set the meter to its highest range first when working with unknown voltages or currents and make a quick measurement at that level to make sure you don't get an overload (OL) on the display. This tells you whether or not you are potentially working beyond the manufacturer specified limits of the equipment (though the manufacturer limits are usually higher than the measurement limits).
eq1) Rseries = R1 + R2 + R3 + ...
eq2) Rparallel = (R1-1 + R2-1 + R3-1 + ...)-1 or eq3) Rparallel = (R1 x R2) / (R1 + R2)
Note the second Rparallel equation can be used for only two resistors.
STEP 1 - Combine all parallel resistance into series resistances using eq2 or eq3.
STEP 2 - Combine all series resistances into a single resistance using eq1.
STEP 3 - Done.
hope this helps.
What has a 555 timer IC in it so I can desolder it and use it?
The LM555 is a highly stable device for generating accurate time delays or oscillation. Additional terminals are provided for triggering or resetting if desired. In the time delay mode of operation, the time is precisely controlled by one external resistor and capacitor. For astable operation as an oscillator,
the free running frequency and duty cycle are accurately controlled with two external resistors and one capacitor. The circuit may be triggered and reset on falling waveforms, and the output circuit can source or sink up to 200mA or drive TTL circuits.
There is little point in desoldering one since they are very cheap to buy since the chip is nearly thirty years old.
NE/SA/SE555/SE555C Timer circuits are all over the net.
