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System Chain Analyzer

Walk a machine system from power supply through driven equipment. See where the risk lives, what probably changed, and what to measure next.

A higher-level system view that walks the user through the four chain links of a rotating machine: electrical supply, motor, belt or coupling or gearbox, and driven equipment. Type in what you can measure (voltage, wire size, run length, motor HP, nameplate RPM, present amps, sheave diameters, gearbox ratio, expected driven RPM), and the analyzer classifies risk at each chain point, infers what probably changed, runs affinity-law reality checks on centrifugal pumps and fans, matches symptoms to common failure modes, and links out to the dedicated single-purpose ToolGrit calculators for any link that needs deeper analysis. Every uncertain output carries an explicit confidence level. When data is missing, the tool tells you exactly what to measure next instead of dead-ending. Built like a senior maintenance planner walking the equipment with you.

Pro Tip: The fastest way to find a system problem is not to dig deeper into one link. It is to see the whole chain at once and ask which link does not match the others. A 5-second look at the System Status card and the colored chain diagram will often surface the bad link before you have your meter out. The "What Probably Changed" panel reads the cross-link evidence the same way an experienced planner does, then tells you the most likely root cause with a confidence level so you know whether to act or verify first.

Read the system chain analysis guide for the full workflow

System Chain Analysis Guide →

Field-first sheave swap workflow with belt section ID and reality checks

Sheave & Belt Field Calculator →

Engineering belt drive sizing with service factors and HP rating per belt

Belt Drive Calculator →

Project pump or fan flow, head, and HP after a speed change

Pump Affinity Laws Calculator →

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System Chain Analyzer
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How It Works

  1. Enter What You Can Measure for the Electrical Supply

    Voltage, phase (1-phase or 3-phase), breaker rating, wire gauge, and one-way run length. Skip anything you cannot read off a panel cover or a wire jacket. The analyzer cross-checks the breaker against NEC 430.52 motor branch-circuit limits using NEC Table 430.250 FLA (3-phase) or Table 430.248 FLA (1-phase) — never nameplate. The wire ampacity is checked against NEC 430.22 at 125 percent of the same table FLA. The running voltage drop is checked against the NEC 210.19 / 215.2 informational target.

  2. Enter the Motor Nameplate

    HP, full-load RPM, poles, full-load amps, service factor, and the present clamp-meter reading at normal load. Tap the 1750 / 3450 / 1160 / 875 RPM presets for typical NEMA motors. The analyzer infers pole count from RPM, computes synchronous speed and slip, calculates nameplate torque, and runs a present-amps overload check against the service factor.

  3. Pick the Transmission Type

    Direct coupled, V-belt, gearbox, or chain. For belts: enter sheave outside diameters and (optionally) center distance. For gearboxes and chains: enter the ratio and the efficiency if you know it. The analyzer computes driven RPM, output torque, belt speed in FPM, wrap angle on the small sheave, and flags geometry that is physically impossible (overlapping sheaves, belt FPM above the cast-iron rim-speed limit, wrap angle below 120 degrees, single-stage ratio above 8 to 1, or a high-ratio worm gearbox with default 70 percent efficiency).

  4. Pick the Driven Equipment Type

    Centrifugal pump, centrifugal fan, centrifugal blower, positive-displacement Roots blower, positive-displacement pump, reciprocating compressor, screw compressor, conveyor, auger, mixer, or machine tool. Enter the expected driven RPM and your strobe-tach reading. The analyzer applies the affinity laws (cube law for centrifugal, linear for positive-displacement, none for conveyors and machine tools), projects the head, flow, and power changes, and warns when projected head exceeds seal or stall limits, when projected power exceeds motor service factor, when NPSH margin is degrading, when the driven equipment is being approached or exceeded on max RPM, or (for non-affinity loads like conveyors) when calculated driven RPM differs from expected by more than 5 percent.

  5. Add Symptoms (Optional but Powerful)

    Type what you are seeing or hearing in plain English: "breaker trips on start", "motor frame is hot", "belt squealing", "pump rattling like marbles", "fan airflow dropped". The analyzer scores your text against a library of common chain failure modes drawn from NEMA AB-4 motor diagnostics, Gates and Browning belt troubleshooting, AMCA 201 fan stall guidance, and Hydraulic Institute pump cavitation criteria. Matches show up as chips on the chain diagram so you can see which link is most likely the culprit.

  6. Read the Verdict and the Five Output Cards

    A single OK / CAUTION / DANGER status combines all four chain segment tiers and the symptom matches. The Risk Score gauge shows the four sub-scores summed to a 0 to 100 total. Below the verdict you get the full Chain Summary table, the What Probably Changed inferences with confidence chips, the never-dead-end What to Check Next measurement queue, and the Related ToolGrit Calculators panel that links to the dedicated single-purpose tool for any link that needs more analysis.

Built For

  • Maintenance planner walking a noisy fan or pump skid and trying to figure out which of the four chain links is actually the problem
  • Reliability tech inferring what someone changed last shift after equipment behaviour shifted unexplained
  • Plant engineer working out whether a proposed sheave or motor change is safe before approving the work order
  • Foreman verifying that a recent retrofit (new motor, new sheaves, new feeder run) is actually consistent across the chain
  • Energy auditor identifying oversized motors or undersized wire on a 24/7 production line
  • Contractor commissioning a new line and confirming that breaker, wire, motor, drive, and equipment all match the design intent
  • Service tech triaging a customer call before they leave the shop, deciding what tools and parts to bring
  • Estimator scoping a repair quote and predicting whether a sheave swap alone will fix the symptom or whether the chain needs broader changes

Features & Capabilities

Whole-Chain Orchestrator, Not a Single Calculator

Walks the user through four chain links — electrical supply, motor, transmission, driven equipment — and combines the segment tiers into a single system verdict. Other ToolGrit calculators dive deep on one link; this one shows you which link to dive into first.

NEC Compliance Checks Built In

Wire ampacity vs Table 430.250 FLA × 125 percent (NEC 430.22), breaker sizing vs Table 430.52 with 250 percent typical cap and 400 percent absolute ceiling per Exception 2(c), running voltage drop vs the 3 to 5 percent informational target (NEC 210.19 / 215.2), and a hard DANGER above 8 percent. Both wire and breaker basis use Table 430.250 FLA, never the nameplate (NEC requires the table value). Routes voltage to the correct NEC 430.250 column (230V, 460V, or 575V) for 3-phase motors and Table 430.248 (115V, 200V, 208V, or 230V) for 1-phase motors automatically. Aluminum conductors trigger a CAUTION because the table assumes copper.

Section-Aware Belt Speed Limits + Minimum Sheave OD Enforcement

Classical V-belt sheaves are limited to 6,500 FPM by cast-iron rim speed (Gates / MPTA). Narrow V-belt sheaves (3V, 5V, 8V) in ductile iron with dynamic balance can run to 10,000 FPM. The analyzer reads your belt section and applies the correct ceiling, so a properly engineered narrow-belt drive does not false-flag DANGER. The analyzer also enforces RMA IP-20 / IP-22 minimum sheave OD per belt section: a B-section belt on a sheave below 5.4 inches, a 5V on a sheave below 7.1 inches, or a 3V on a sheave below 2.65 inches all trigger a CAUTION below the published minimum or a DANGER below 85 percent of the minimum, because the belt rating and life are invalid at those diameters.

NEMA-Aware Motor Analysis

Synchronous RPM from pole count, slip from nameplate RPM, pole count inference for missing data, torque from HP and RPM, present-amps overload check against service factor (1.00 / 1.15 / 1.25). Accepts NEMA Design D high-slip motors (5 to 13 percent slip) without false-flagging.

Affinity-Law Reality Check

For centrifugal pumps, centrifugal fans, centrifugal blowers, and mixers: applies the cube law (Q proportional to N, H proportional to N squared, P proportional to N cubed) and projects head, flow, and HP changes. Warns at head ratio above 1.21 (CAUTION) and 1.5 (DANGER) for seal and ductwork limits, HP ratio above 1.15 (motor service factor) and 1.40 (motor cannot absorb), and any speed bump above 5 percent (NPSH margin reminder for pumps). Positive-displacement Roots blowers and PD pumps follow linear flow scaling instead. Conveyors, augers, and machine tools follow neither, but a speed mismatch greater than 5 percent from expected still triggers a CAUTION because that level of drift indicates a design or component change.

Worm-Gearbox Efficiency Awareness

Single-reduction gearbox at high ratio (above 30 to 1) is almost always a worm. Default efficiency drops to 70 percent automatically because high-ratio worms run 50 to 70 percent, not the 95 percent of a helical or bevel single-stage. Otherwise output torque gets overstated by 30 to 40 percent.

Symptom-to-Cause Matcher

Type plain-English symptoms and the analyzer scores them against a library of common failure modes. Matches are routed to the right chain segment so the verdict bucket reflects which link is most likely failing. Each match includes severity, likely causes, and a recommended action drawn from NEMA, Gates, AMCA 201, ISO 10816-3, and Hydraulic Institute references.

Never Dead-Ends

When inputs are missing, the What to Check Next panel populates with the specific measurement, why it matters, and how to take it in the field. Voltage drop missing wire gauge? Reads "Look at the printed legend on the conductor jacket inside the panel or disconnect." Motor RPM missing? Reads "Look for FL RPM on the motor nameplate." No insufficient-data error states. Always actionable.

Confidence Levels on Every Output

Inferences (what probably changed), symptom matches, and missing-data flags all carry an explicit high / medium / low confidence chip. The tool would rather tell you it does not know than guess.

Live System Chain Diagram

A live SVG shows five colored nodes (power, motor, transmission, driven, symptoms) updated as you type. Nodes are clickable so you can jump straight to the step panel that corresponds to the worst-tier segment. Tier colors match the verdict colors so the chain reads at a glance.

Risk Score Gauge

Four 0 to 25 sub-scores (electrical, motor, transmission, driven equipment) summed to a 0 to 100 total. Triage scoring, not engineering certification. Below 45 = low risk; 45 to 69 = moderate; 70 and up = high. Aria-live so screen readers announce the score change as you edit inputs.

Cross-Link Prefill Panel

Related ToolGrit Calculators panel groups cross-links by chain segment and includes a one-line "why this tool" explanation. Each link carries query-string state so the destination calculator can prefill from the chain analysis (HP, voltage, sheave diameters, expected RPM). Future-proofed for sister tools to backfill prefill support.

Comparison

Chain Link Inputs Key Outputs Standards Cited
Electrical supply V, phase, breaker A, AWG, run length, conductor NEC FLA, Vdrop %, ampacity headroom, breaker sizing % NEC 2023 Tables 430.248, 430.250, 430.52; Ch. 9 Table 8
Motor HP, FL RPM, poles, FLA, SF, present amps, η, PF Sync RPM, slip %, torque, FLA basis, present amps % FLA NEMA MG-1; NEC 430.22, 430.32
Transmission (belt) Driver and driven OD, center distance, belt section Driven RPM, ratio, belt FPM, wrap angle, output torque RMA IP-20 / IP-22; Gates / MPTA design data
Transmission (gearbox / chain) Ratio, efficiency Output RPM, output torque AGMA, ANSI B29 (chain), worm efficiency tables
Driven equipment Type, expected RPM, observed RPM, max RPM override Affinity factors, head and HP delta, max RPM check Hydraulic Institute (HI), AMCA 201 (fans)
Symptoms Free text Matched library entries with severity and action NEMA AB-4, Gates / Browning, AMCA, ISO 10816-3

Assumptions

  • NEC FLA values are looked up from Table 430.250 (3-phase, 230V / 460V / 575V columns) or Table 430.248 (1-phase, 115V / 200V / 208V / 230V columns) and interpolated between HP rows. Wire ampacity (NEC 430.22) and breaker sizing (NEC 430.52) both use the NEC table value when available; when HP, voltage, or phase falls outside the table, the analyzer falls back to nameplate with a CAUTION explaining the strict NEC basis is missing. Nameplate FLA is the primary basis for present-load and overload analysis (NEC 430.32) only.
  • Voltage drop uses NEC 2023 Chapter 9 Table 8 copper resistance at 75 degrees C. Aluminum conductors require AL-rated terminations and a different resistance table.
  • Belt drive math uses sheave outside diameter as a working stand-in for pitch diameter. Treat outputs as field estimates; pitch diameter is roughly 0.2 to 0.5 inches less depending on belt section.
  • Belt-speed DANGER threshold is 6,500 FPM for classical V-belt sheaves (cast-iron rim speed limit per Gates / MPTA) and 10,000 FPM for narrow V-belt sheaves in ductile iron with dynamic balance.
  • Affinity-law cube-law projections apply to centrifugal pumps, centrifugal fans, centrifugal blowers, and mixers. Positive-displacement equipment (PD pumps, Roots blowers, reciprocating and screw compressors) scales linearly with speed at constant pressure. Conveyors, augers, and machine tools follow neither but still surface a CAUTION when the calculated driven RPM differs from expected by more than 5 percent.
  • Gearbox default efficiency: 95 percent for single-stage helical or bevel up to 30 to 1, 70 percent for high-ratio worm above 30 to 1, 97 percent for chain. Override with the nameplate value when known.
  • Risk-score weighting (electrical / motor / transmission / driven equipment, 0 to 25 each) is a triage tool, not an engineering certification.
  • Confidence levels (high / medium / low) are explicit on every uncertain output. Low-confidence answers are starting points for further measurement, not final answers.

Limitations

  • Does not perform full NEC short-circuit calculation, fault current analysis, or arc-flash incident-energy modelling. Use a dedicated SKM, ETAP, or EasyPower tool for those.
  • Does not size mechanical seals, bearings, couplings, or shafts to a specific service factor or fatigue life. Use the dedicated single-purpose ToolGrit calculators or the manufacturer engineering tools.
  • Does not model harmonics, VFD-induced motor heating, or PWM-related cable derating.
  • Does not predict or model startup transients, locked-rotor torque profiles, or motor acceleration time.
  • Does not model gear tooth contact, tooth bending stress, or specific gearbox lubrication regime; treats gearbox as a ratio and efficiency black box.
  • Does not predict belt life, bearing life, or service interval; does not replace condition monitoring.
  • Symptom matcher is keyword-based against a fixed library; does not interpret photos, audio, or vibration spectra.

References

  • NEC 2023 Article 430 (Motors, Motor Circuits, and Controllers) and Tables 430.248, 430.250, 430.52.
  • NEC 2023 Chapter 9 Table 8 (conductor properties) and Table 310.16 (allowable ampacities).
  • NEMA MG-1 (Motors and Generators), synchronous speed, slip, service factor, design letter classifications.
  • RMA IP-20 (classical V-belt) and IP-22 (narrow V-belt) cross-section standards.
  • Gates Industrial Power Transmission Design Manual.
  • MPTA (Mechanical Power Transmission Association) belt drive standards.
  • Hydraulic Institute (HI) standards for centrifugal pump performance and affinity laws.
  • AMCA 201 (Fans and Systems), fan-stall and ductwork-pressure considerations.
  • ANSI / ASME B29 chain drive standards.
  • AGMA gear standards for helical, bevel, and worm gearbox performance.
  • ISO 10816-3 vibration severity zones for rigid-mount industrial machines.
  • NEMA AB-4 motor diagnostics and failure analysis.

Frequently Asked Questions

Each single-purpose calculator goes deep on one chain link. Belt Drive Calculator dives into V-belt sizing with service factors and HP rating per belt. Wire Sizing Calculator dives into NEC ampacity tables. Pump Affinity Laws Calculator dives into flow, head, and power scaling. The System Chain Analyzer takes one step back and asks "which link is the problem?" — it walks the whole chain at once, gives you a single verdict, and tells you which link to dive into next using the dedicated tool. The Related ToolGrit Calculators panel is the bridge: every chain segment has prefill cross-links to the right deep-dive calculator. The two layers complement each other; this tool does not replace them.
Yes. The What to Check Next panel populates with specific measurements you can take in the field, why each matters, and how to take it. If you only have voltage and breaker rating, the analyzer routes you to read the motor nameplate. If you have nameplate but no clamp-meter reading, it tells you to take a present-amps reading at normal load. The tool is designed not to dead-end, and missing data forces the verdict to "Inputs incomplete — cannot certify safe" rather than letting it return a false OK.
Both NEC 430.22 (conductor ampacity) and NEC 430.52 (motor branch-circuit short-circuit and ground-fault protection — the breaker) require sizing based on Table 430.250 FLA for 3-phase motors or Table 430.248 FLA for 1-phase motors. High-efficiency motors often have nameplate FLA LOWER than the table value, and using nameplate would under-size the wire AND artificially inflate the breaker percentage (making a correctly sized breaker appear oversized). Both protective device sizing rules use table FLA because that is the worst-case current under any nameplate variant. Overload-relay sizing (NEC 430.32) is the only path that uses nameplate FLA. The analyzer keeps the three rules separate so the protective devices never get sized incorrectly.
Centrifugal pumps and fans follow the affinity laws: flow scales with speed, head scales with the square of speed, and power scales with the cube. A 10 percent speed bump pushes power to 133 percent of original. The reality check uses your expected driven RPM (the design baseline) and the calculated driven RPM (current state) to project the rise in flow, head, and HP. Projected HP above 115 percent of original is CAUTION because the typical NEMA service factor is 1.15 and you are eating into it. Above 140 percent is DANGER because the motor cannot absorb that without upsizing. Projected head above 121 percent triggers seal-pressure and ductwork-stall warnings. The current clamp-meter reading you enter is a SEPARATE direct overload check (above 100 percent FLA = DANGER, above 90 percent = CAUTION); the tool does NOT multiply that present reading by the speed factor because it is a current state, not a baseline.
The Risk Score and the System Verdict are two different things. The verdict short-circuits to DANGER on any single DANGER warning across the chain — that is the safety-first behaviour. The Risk Score is a 0 to 100 triage number that reflects how stacked the cautions and dangers are across all four segments. A single DANGER in one segment lights up the verdict but only contributes 22 to 25 points to the score. Two danger segments stacked plus minor cautions elsewhere will move the score into the 70+ range. The verdict is binary safety, the score is depth of trouble.
The links carry query-string parameters (HP, voltage, sheave diameters, expected RPM, etc.) so a destination calculator can read them and prefill its inputs. Some destination calculators already accept these parameters; others will accept them as we backfill. The fallback is harmless: if a destination ignores the query string, the user just lands on the calculator as usual. The panel always shows the slug-level destination so the user can verify they are landing on the right tool.
Single-stage gearboxes above about 30 to 1 are almost always worm gearboxes. Worm efficiency is heavily ratio-dependent — a 60 to 1 worm typically runs 50 to 70 percent efficient, not the 95 percent of a helical or bevel single-stage. If the analyzer used 95 percent for a 60 to 1 worm, it would overstate output torque by 30 to 40 percent — a number the user would actually believe. The default drops to 70 at high ratio so the output torque is plausible. If you have a real efficiency value from the nameplate or a manufacturer datasheet, enter it and override the default.
No. The default state (10 HP / 480V / 3-phase, 1750 RPM motor on a 5.4-inch / 12-inch V-belt drive to a centrifugal pump expecting 800 RPM, with a 30 A breaker and AWG 10 wire on a 100 ft run) was deliberately chosen to land on a healthy benign verdict so first-time users see what a passing chain looks like before they start typing in their own numbers. Healthy default = green chain, then the user edits inputs and watches the diagram change as they introduce real-world deviations.
Disclaimer: Outputs are field engineering estimates based on standard NEC, NEMA, RMA, MPTA, AMCA, Hydraulic Institute, and ISO references. Actual chain performance depends on installation alignment, belt tension, lubrication, environmental conditions, and equipment loading not captured by simple inputs. The analyzer is a triage tool, not an engineering certification: the verdict is a starting point for further inspection, not a final answer. Confidence levels are explicit; treat low-confidence outputs as starting points for further measurement. ToolGrit is not responsible for equipment damage or failure resulting from any decision made using this tool.

Learn More

Industrial

System Chain Analysis Guide: Read a Whole Machine as One Chain

How to walk a rotating-equipment system from electrical supply through motor, transmission, and driven equipment, find which link is the problem, and pick the right field measurement to take next. Companion to the System Chain Analyzer.

Read Guide →

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