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.
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.
The megger leads are connected in the following manner. Black lead to motor ground terminal or motor frame. The other lead to one of the phase wires. Meg that coil to ground and note the reading. Do the same with the other two motor leads and note the readings. Look at all of the three reading that you have taken. Engineers like the reading to be above 5 meg. Preferred readings about 2 meg. Motor needs looking after below 1 meg.
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.
Engineers that I have worked with state in their specifications that all meggered wires must have a reading of 5 Meg ohms or higher. If the reading is lower that this benchmark start checking splices especially if it is an underground installation. Water usually accumulates in underground conduit systems and when the wires are pulled in there is a certain amount of conductor scraping. This starts the downward spiral from infinity. Check termination points close to the exit point of the conduit. A certain amount of evaporation from the conduit condensates on the terminal points.
If it is a motor connection that is being tested, engineers like to see it above 5 meg. In reality above 2 meg is fine.
with an meg ohm meter
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.
The megger leads are connected in the following manner. Black lead to motor ground terminal or motor frame. The other lead to one of the phase wires. Meg that coil to ground and note the reading. Do the same with the other two motor leads and note the readings. Look at all of the three reading that you have taken. Engineers like the reading to be above 5 meg. Preferred readings about 2 meg. Motor needs looking after below 1 meg.
The megger leads are connected in the following manner. Black lead to motor ground terminal or motor frame. The other lead to one of the phase wires. Meg that coil to ground and note the reading. Do the same with the other two motor leads and note the readings. Look at all of the three reading that you have taken. Engineers like the reading to be above 5 meg. Preferred readings about 2 meg. Motor needs looking after below 1 meg.
three
1.46 meg ohm
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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.
they are (1) meg had to name the principal (2) she had to convince the mitochondria to grow into adults (3) meg had to save her principal from the echidorms
The Griffins have three kids: Chris, Meg, and Stewie
gryh
Meg goes through the Dark Thing whilst tessering. Since her father was inexperienced and Meg wasn't good at tessering, she became temporarily paralyzed. Calvin and Mr.Murry are talking about what happened before the three came when Meg starts to feel again. Some monsters came and took care of Meg until she was fully recovered. Then the three Mrs.Ws come to bring Meg away to save her brother. Calvin and Mr.Murry become angry. When she leaves Meg hugs Aunt Beast (the beast that took care of Meg), and Calvin kisses her, and Mr.Murry hugs his eldest child and only daughter.