Does the ground have to be on X2?

[foo]

In this schematic there is two potential transformers on the left and two current transformers on the right.

The potential transformers on the left are connected together by a wire between X2 of the left transformer and X1 of the right transformer. Then there is a wire that must come from one of these two transformers to the test switch location that also has a ground connected to it.

My first question on this is, does the wire that connects these two ends of the transformer to the switch have to be connected to X2 in that part or can it be connected to the X2 or X1 of those two directly connected terminals?
I ask because I notice that the schematic rearranged the way that the current transformers on the right are oriented so that the X2 wires that are going to the switch will also be grounded. Althought they are not connected in series with each other like the left ones are.

My second question is, are the potential and current coils connected at the tops past the switch so much less resistant than the Earth ground that an Earth ground can be connected in this way without causing a short? Will only excessive current go to ground? And under what kind of conditions will current decide to go to ground?

 

[dlgoff]

I see nothing wrong with the wiring here. Ground is just your reference when taking measurements (I assume the components above your test switch are meters). The voltage transformers are wired so that the connection of X2 and X1 is like a center tap. You are measuring the voltage of each leg to ground; (they are usually wound to provide a nominal operating voltage of 115Vac which represents the lines higher voltage). And the current transformers are wired to measure the current through each leg; (they are usually wound to provide a nominal operating voltage of 115Vac which represents the lines normal current).

Note that the test switch shorts out the CTs secondary when the switch is open (not taking a reading).

 

[oswaler]

I cannot provide a definitive answer without more information about the specific schematic and application in question. However, I can offer some general insights and considerations.

Firstly, the ground connection is an important safety measure in electrical systems. It helps to protect against electric shocks and can also help to reduce noise in the system. In most cases, the ground connection should be made to the ground terminal (usually labeled as "GND") on the potential or current transformer.

In terms of the specific wiring arrangement mentioned in the content, it is important to follow the schematic provided and ensure that all connections are made correctly. The purpose of the wire between X2 of the left transformer and X1 of the right transformer may be to ensure proper phase alignment between the transformers. Connecting this wire to any other terminal may result in incorrect phase alignment and could potentially affect the accuracy of the measurements.

As for the second question about current going to ground, this would depend on the specific conditions and variables in the system. Generally, current will only flow to ground if there is a path with low resistance, such as a direct connection or a fault in the system. The potential and current coils should be designed to have a higher resistance than the ground connection, so current would not typically flow through them to ground. However, if there is a fault or other abnormal condition in the system, it is possible for some current to flow to ground.

In conclusion, it is important to carefully follow the provided schematic and make all connections as indicated. If there are any concerns or questions about the wiring or safety of the system, it is best to consult a qualified electrician or engineer for assistance.

 

[oswaler]

I cannot definitively answer these questions without more context and information about the specific schematic you are referring to. However, based on the information provided, it appears that the ground does not necessarily have to be on X2 in this setup. The wire connecting the two transformers can be connected to either X1 or X2, as long as it is connected to the correct corresponding terminal on the other transformer. The arrangement of the current transformers on the right may be different due to the specific wiring setup of the system.

Regarding the second question, it is important to note that the potential and current coils are designed to have different resistances and are typically connected in parallel. This means that the potential coil will have a higher resistance than the current coil, allowing for the proper measurement of voltage and current. As for the Earth ground connection, it is possible that the system is designed to handle excessive current and only allow it to go to ground in certain conditions, such as a fault or overload. However, without more information, it is difficult to determine how the system will behave in different scenarios. It is important to consult the schematic and any relevant documentation to fully understand the design and function of the system.