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How do you connect a megger on a three phase wye - wye transformer for testing?
Wiki User
∙ 11y ago
First you would disconnect the HO bushing connection from ground. Then you would megger low-side phase to ground.. Next you would megger high-side phase to ground.. Lastly megger high-side to low-side phase to phase. You would not megger phase to phase on each side because this is a direct connection.
Wiki User
∙ 12y ago
Wiki User
∙ 11y agoto check if the motor is grounded, you put the megger to the voltage section, one of the lead goes to the groung lug and the other lead goes to 1 wire of the three phase motor. You do this for all 3 wire of the motor. You suppose to have the reading in the Mega ohm.
to check if the motor is shorted phase to phase, put the megger in ohm section and put one lead to a motor wire and the other lead to another wire. Do it like this A-B / B-C / A-C and the 3 reading should be almost equal.
Wiki User
∙ 11y agoAnswer for USA, Canada and countries running a 60 Hz supply service.
First the transformer has to be isolated from all of its connections if it is not a new installation. This includes primary and secondary feeders. Remove the bond strap from the neutral to the transformer case. If possible separate the primary and secondary neutral connection. This should leave the transformer coils isolated from the transformer case. Connect one lead of the megger to any of the primary lead coils. The other primary coils will be also checked through the common neutral. Connect the other lead to the transformer case. Select the correct voltage range on the megger and do the test. Do the same test on the secondary side of the coils. The reading should be in the range of 5 meg ohms to be usable.
As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
Before you do any work yourself,
on electrical circuits, equipment or appliances
always use a test meter to ensure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
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How do you meg a three phase padmount transformer?
Three-phase, pad mounted, transformers are normally 'pressure tested' i.e. subjected to a DC over-voltage for a specific period of time, using high-voltage test equipment rather than a megger as a megger's output voltage is usually far below the voltage-levels required for testing such transformers. The voltage/duration is in accordance with the transformer's relevant specifications which takes into account its windings' rated voltages. Pressure testing is performed in factory/workshop and after installation before commissioning.
Load test on single phase transformer?
The dc tests that can be done on a transformer are to measure the resistance of each windings and to measure the insulation resistance between the windings and between each winding and the transformer case.
What is phase shift in three phase transformer?
The phase shift in three-phase transformer from winding of Transformer and determine by vectorgroup of transformer such as YNd1 High voltage connect to wye Low Voltage connect to delta so L.V. lag H.V 30 degree.Answer'Phase shift' or, more accurately, 'angular displacement', is the angle between the secondary line voltages and primary line voltages of a three-phase transformer.
Why vector group is required?
There are various ways in which you can connect a three-phase transformer's primary and secondary windings, or in which you can connect three single-phase transformers to create a three-phase transformer bank. For example: wye-wye, wye-delta, delta-delta, delta-wye, etc.For each connection, there is a natural phase shift between the primary and secondary line voltages. This is called the angular displacement (or 'phase displacement') of the transformer connection.If you wish to parallel two three-phase transformers, or two three-phase transformer banks, then their angular displacements must be the same (there are also other requirements not relevant to this answer).A vector group is a method of specifying a three-phase transformer (or transformer bank) method of connection and its angular displacement. Transformer connections from the same group can be paralleled. Those in different groups cannot
How do you connect ammeter with ct in single phase?
If it's a split-phase system with centre-tapped transformer, then two ammeters are needed, one on each side.
How do you meg a three phase padmount transformer?
Three-phase, pad mounted, transformers are normally 'pressure tested' i.e. subjected to a DC over-voltage for a specific period of time, using high-voltage test equipment rather than a megger as a megger's output voltage is usually far below the voltage-levels required for testing such transformers. The voltage/duration is in accordance with the transformer's relevant specifications which takes into account its windings' rated voltages. Pressure testing is performed in factory/workshop and after installation before commissioning.
Load test on single phase transformer?
The dc tests that can be done on a transformer are to measure the resistance of each windings and to measure the insulation resistance between the windings and between each winding and the transformer case.
How do you connect an earthing transformer with delta connected secondary?
You have to connect each phase (R,Y & B respectively) of earthing transformer zig zag winding to each phase of power transformer delta secondary respectively. Then the zig zag winding of earthing transformer star point to be earthed.
How many 16 Amps per phase welding outlet can you install to a 30 KvA rating transformer?
..the questions does not say wether the 30kVA transformer is 3 phase transformer or single phase transformer..but it is implying that a single phase welding load at 16A per phase is to be connect to it, it is assumed then that the transformer is 3 phase transformer..we assume load is rated 240V.. ..though not much details is given about the transformer voltage specs. but if is rated 3 phase 415/240V, the approx full load current per phase is given by 30KVAx1.3912=41.736A.. ..but if the transformer was rated single phase 240V say, the approx full load current FLC=30000/240V gives 125ampers.. ..if you further devide the FLC by the intended load current.. ..Recommended no of welders per for a 3 phase 415V transformer and assuming single welding sets =41.736/16=2.6..so you can connect max two welding sets to this transformer per phase,..max 6 weld sets can connect at an approx load factor of 76%.. ..for the single phase transformer, FLC/16=125/16, gives 7.8 but is also recommended not to connect more than 6 welding sets to such transformer for the same reasons..
How do you connect 480 vac three phase power to a 480 vac single phase transformer?
If the primary and the secondary windings of the three phase transformer are connected in delta, you cannot get a healthy neutral from it but why bother? You simply drive a rod into earth and use it as a neutral. Alternatively either the primary or the secondary windings must be connected as star and you use the common point as neutral.
What is phase shift in three phase transformer?
The phase shift in three-phase transformer from winding of Transformer and determine by vectorgroup of transformer such as YNd1 High voltage connect to wye Low Voltage connect to delta so L.V. lag H.V 30 degree.Answer'Phase shift' or, more accurately, 'angular displacement', is the angle between the secondary line voltages and primary line voltages of a three-phase transformer.
Why vector group is required?
There are various ways in which you can connect a three-phase transformer's primary and secondary windings, or in which you can connect three single-phase transformers to create a three-phase transformer bank. For example: wye-wye, wye-delta, delta-delta, delta-wye, etc.For each connection, there is a natural phase shift between the primary and secondary line voltages. This is called the angular displacement (or 'phase displacement') of the transformer connection.If you wish to parallel two three-phase transformers, or two three-phase transformer banks, then their angular displacements must be the same (there are also other requirements not relevant to this answer).A vector group is a method of specifying a three-phase transformer (or transformer bank) method of connection and its angular displacement. Transformer connections from the same group can be paralleled. Those in different groups cannot
How do you connect ammeter with ct in single phase?
If it's a split-phase system with centre-tapped transformer, then two ammeters are needed, one on each side.
What is the current of 1MVA transformer?
This depends on the voltage, and whether it is a three phase or single phase transformer.
Can you connect 480 volt 3 phase WYE POWER to a 3 phase 480 volt delta primary transformer?
Probably not, in the case of a three-phase transformer as it has been pre-connected, enclosed in a metal tank, fitted with the appropriate bushings, etc.. However, it is a relatively straightforward job in the case of a three-phase transformer bank that comprises three separate, single-phase, transformers. Whether you'll obtain your desired secondary voltage is another matter.
How can you connect current transformer to ammeter in three phase?
You use three CTs, one per line conductor, each feeding a separate ammeter,
What is a battery method of a single phase transformer?
Connect a VOM to one winding. Momentarily connect a battery to the other winding. When the battery makes contact, a pulse will occur on the other winding. If the pulse is positive, then the terminal connected to the plus lead is in phase with the lead connected to the battery.
