sharpie7
BUG- AC Sources output incorrect RMS values (w/ clearly labeled example circuits)
I wired up a Delta/Wye transformer and when inputting max (peak) voltage for each incoming source I needed to input 98V to get an RMS of 120V it should be 170V required max (peak) to yeild 120 RMS. It seems like there is an internal scaling error where the AC source behaves like a 3 phase Wye generator, where whatever value is inputted in the "max voltage" field, is instead treated like a Line to Neutral value. Which is then multiplied by the square root of three before reaching the circuit behaving like a line to line voltage value. The oscilloscope view also does not align with what is measured with the voltmeter after I found a fix.
In the examples every AC source is set to 98V max voltage if you change it to the expected 170 peak voltage everything else goes much higher than it should.
If you measure with the voltmeter from any phase of the delta's inputs to ground on the two terminal example the RMS values are correct just not from phase to phase.
EXAMPLE CIRCUITS single terminal AC: https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWECBs0DMlMCZ0oBzoICcCYYALMpMtcgKYC05AUAO4gDse4x2yfXv0jsB-MIJL8pUUTJncUY2R0Uhsnfik3qdIjtv4atOvPhUhDIM1x439tpRQrmrz8w7cvLOssNFWfo7IYP4chEY6+MRKxhbRsVExIO7xyakRKd4OmTIJyjnJeenZosTO1gQgxIL2ormh1RVBDhTo0o2BjZ6mVW38dRwyEvz9QrIAHsj4EChzlihIc8SWlSAAIvQANgAuAIYsU8SdVcSEPrNrAOoAnvSHlvic4JzPnJAQYPg0VNhUADoABweKFqFBW7yURFG6gBwKmBGe4KQ7wg4PMvzhD3IlBSCHQ4AkaNQKVhIAAcvQAK47ABOey29RK5nKVFSDlZWXM5EgbO82AeZxoX3EcCUXyQmJAABkwNi4FR0JxuVgaOgZqS-jKBVMwB9zAhsJ9eVRDWyydL0A90Mkvk5sOJopqqLLrZwoecKJABvgnBaddZSMgjSkQ2bnTKrVMEPgtA6FlQUNhJWSAAq0gCWAFs9rSbg9onHxWLLNgVlKAMr0ADGAHsAHYAE1z+YASil2uMxn8aMLLDQzlAhzAECx22MbGMvb3wP3qh51LByjayN6begJPioNBR+PO0ExggKn2UAOFxRoF8nsRvbzlSgbZAkCOQe9wNglPhzqFy+oaGwAOgAAzBkAGd9kbaA6yzAB6asM1pasqQzHYYIeCgSFhZ5DQJZMfjJSB-lAzYAHN0IQJFIBWI8CQoRopVCQjQMbegyKmDCCQQLd8WokkpR7IiWLIkjCV5LlRLZFAqF7FgABVghGEBMjiGEIBgbAPk4CgCC+ZVlW9J4QEYGB4DXEY-l9cEjSo84YBqYg5OCGxMlSVSjJMsAeKNfpDVePggxM+BcHMlwpL4D8lDsmpHLUIJckENzjMvX10GcbAZhjMBUq9AkktMvUvTaGMsFCd1kzU6B7JYQEmioRTORsAk1PAUz4Gq2rxM5IImqHPVWpEGr0B4ZMoTsMSeuFfqHCG2I+M7RTprGtlO0GDqgj6g1unqebBE5BaygqerBH28IVtOCo6iAA
Double terminal AC: https://www.falstad.com/circuit/circuitjs.html?ctz=CQAgjCAMB0l3BWECBs0DMlMCZ0oBzoICcCYYALMpMtcgKYC05AUAO4gDse4x2yfXv0jsB-MIJL8pUUTJncUY2R0Uhsnfik3qdIjtv4atOvPhUhDIM1x439tpRQrmrz8w7cvLOssNFWfo7IYP4chEY6+MRKxhbRsVExIO7xyakRKd4OmTIJyjnJeenZosTO1gQgxIL2ormh1RVBDhTo0o2BjZ6mVW38dRwyEvz9QrIAHsj4EChzlihIc8SWlSAAIvQANgAuAIYsU8SdVcSEPrNrAOoAnvSHlvic4JzPnJAQYPg0VNhUADoABweKFqFBW7yURFG6gBwKmBGe4KQ7wg4PMvzhD3IlBSCHQ4AkaNQKVhIAAcvQAK47ABOey29RK5nKVFSDlZWXM5EgbO82AeZxoX3EcCUXyQmJAABkwNi4FR0JxuVgaOgZqS-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-jAw2jelBEYulLQzX100UNAXxPCJtG6b6NqEUpw1gWM7Q-DlPBwSwj3peN2WjN8A0fZNe2A16-1AA
I'm not sure I follow all that.. But the AC voltage sources are very simple. They report the peak voltage as Vmax, and then to calculate V(rms) they take the peak voltage divided by sqrt(2).
It seems that you are connecting together two 120V(rms) AC voltage sources with phase separated by 120 degrees, and expecting the voltage difference between them to also be 120V(rms) ? Instead it should be 120 * sqrt(3). So if you want 120 you need two voltage sources of 120/sqrt(3) which is 69 V rms, just like you have in this example.
Thank you for your reply I am a first year electrical systems student I suppose I had not grasped the full concept, I was under the impression all I had to do was supply 3 AC sources 120 degrees out of phase, each with 120 RMS, in a delta configuration and the RMS would remain 120 between phases thank you for the clarification
On Fri, Nov 7, 2025 at 1:40 PM Paul Falstad @.***> wrote:
pfalstad left a comment (sharpie7/circuitjs1#1024) https://github.com/sharpie7/circuitjs1/issues/1024#issuecomment-3504199689
I'm not sure I follow all that.. But the AC voltage sources are very simple. They report the peak voltage as Vmax, and then to calculate V(rms) they take the peak voltage divided by sqrt(2).
It seems that you are connecting together two 120V(rms) AC voltage sources with phase separated by 120 degrees, and expecting the voltage difference between them to also be 120V(rms) ? Instead it should be 120 * sqrt(3). So if you want 120 you need two voltage sources of 120/sqrt(3) which is 69 V rms, just like you have in this example.
— Reply to this email directly, view it on GitHub https://github.com/sharpie7/circuitjs1/issues/1024#issuecomment-3504199689, or unsubscribe https://github.com/notifications/unsubscribe-auth/BZ3JLEU4EEK3EUVJGXDN2VD33TRRZAVCNFSM6AAAAACLOTUVE6VHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTKMBUGE4TSNRYHE . You are receiving this because you authored the thread.Message ID: @.***>