Induction-Machine Signed Slip & Speed Worksheet
Convert measured rotor speed to signed slip,or signed slip to rotor speed,for an explicitly documented induction-machine motoring or generating state. Frequencies are labelled by definition and are not used for automatic fault diagnosis.
Document one operating state
Use supply fundamental and rotor speed from the same stable state. Pole count must come from controlled motor documentation,not from an assumed50/60Hz speed.
Kelajuan segerak
Kelajuan rotor
Signed slip
Signed speed difference
Signed s·f product
Rotor electrical frequency magnitude
Operating mode
Speed difference
Calculation direction
Equations,signs and units
| Kuantiti | Equation | Tafsiran |
|---|---|---|
| Kelajuan segerak | nₛ=120f/P putaran seminit | Rotating-field speed from supply fundamental and pole count. |
| Signed slip | s=(nₛ−n)/nₛ | Positive for this motoring convention;negative for generating above synchronous speed. |
| Inverse speed | n=nₛ(1−s) | s is a ratio;divide entered percent by100. |
| Mechanical speed difference | (nₛ−n)/60 putaran/s | Not the same quantity as rotor electrical frequency when pole pairs exceed one. |
| Rotor electrical frequency magnitude | |s|f Hz | The worksheet also reports signed s·f separately so the generating sign is not silently erased. |
These are induction-machine kinematics and vocabulary-based relations,not ISO10816,ISO21940 or an ISO fault-diagnostic formula.
Sources and applicability
IEC Electropedia defines synchronous speed,IEV411-46-06,as the rotational speed resulting from system frequency and pole count. IEV411-46-07 defines slip from the synchronous-to-actual speed difference expressed per unit or percent of synchronous speed.
IEC60034-1:2026,Edition15 is the current rotating-machine rating/performance standard and replaced2022. Exact rated-speed,marking,tolerance,test and operating requirements remain NEEDS_LICENSED_SOURCE;this worksheet does not infer them.
Interpretation safeguards
- Nameplate speed is a rated value for its stated rating;it is not a substitute for speed measured during another load,supply or converter state.
- Slip is not universally proportional to load across starting,breakdown,field weakening,control modes or abnormal operation. No fixed normal,full-load or severity range is applied.
- The signed mechanical difference and rotor electrical frequency differ by pole-pair scaling;the former page labelled duplicate outputs without explaining that boundary.
- Frequency candidates around supply harmonics require adequate spectral resolution,load-matched baselines and corroboration. This worksheet makes no broken-bar or eccentricity diagnosis.
- Generating-mode arithmetic does not approve grid connection,prime mover,protection,converter or overspeed operation.
Perkara yang telah dibetulkan
The former inverse mode accepted arbitrary slip above100% and could display negative rotor speed. Its speed mode silently allowed generation but then erased the slip sign with Math.abs,while “slip frequency” and “rotor frequency” displayed the same number without a clear signed/magnitude distinction.
Defaults,presets,50/60Hz geography assumptions,URL/history persistence,partial pole menus,universal NEMA/no-load/full-load slip bands,breakdown-torque claims and automatic rotor-fault advice were removed. The replacement requires explicit motoring/generating basis,same-state sources,strict parsing and physically consistent sign gates.
