ESA, MCSA and vibration analysis: what to choose for CHP auxiliary equipment

At CHP and thermal power plants the auxiliary equipment — make-up pumps, ID fans, boiler feed pumps, condensate pumps, cooling fans — is often left out when a predictive maintenance programme is built. Yet these are exactly the machines that keep the main cycle running. Three methods compete for the maintenance budget: vibration analysis, MCSA (current analysis) and ESA (full electrical analysis). Let us see which to choose when.

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Brief definition of the methods

Method	What is measured	Where the sensor goes
Vibration analysis	Acceleration / velocity / shaft displacement	On the bearing or the housing
MCSA	Current (sometimes a single phase)	Current transformer in the cabinet
ESA (Artesis)	Current plus voltage, all phases, spectrum, power	In the motor control cabinet

MCSA is a subset of ESA. Artesis performs a full spectral analysis of current and voltage against a motor model, not just "peaks at running speed".

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Vibration analysis: strengths

Best suited for:

• steam and gas turbines, generators (high vibration energy);
• large fans and ID fans with permanent access to the bearings;
• equipment that already has a Bently Nevada 3500 system installed.

Limitations on CHP auxiliaries:

• small machines (<75 kW) give a weak vibration signal;
• frequent duty changes (VFD) complicate thresholds;
• mounting sensors in dusty, hot zones is expensive and hazardous;
• diagnosing the electrical part (winding, rotor) is impossible with vibration.

Material on CHP vibration monitoring: 3500/42M on auxiliary machines, four PdM methods.

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MCSA: fast screening

Pros: low entry cost, connection in the cabinet, no access to the machine required.

Cons:

• without voltage and a motor model there are more false alarms;
• weak diagnosis of process faults (cavitation, blockage);
• limited operation with VFDs unless specially configured.

MCSA makes sense as a first filter, but for critical CHP pumps it is usually not enough.

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Artesis ESA: the comprehensive view

Artesis e-MCM analyses:

• mechanics — bearings, unbalance, misalignment, gear meshes;
• electrics — windings, rotor, phase asymmetry, harmonics;
• process — cavitation, overload, operation away from the pump BEP.

Installation in the cabinet takes 1–2 hours with no shutdown. ATEX compatibility: the sensors are not in the hazardous zone.

A typical CHP scenario: e-MCM on the condensate and feedwater pumps, AMT Pro on the rest of the auxiliary drive fleet.

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Selection matrix for CHP / metals plants

Situation	Recommendation
Turbo-generator, steam turbine	Bently Nevada, vibration plus key phases
ID fan >500 kW	Online vibration plus ESA as a supplement
Pumps 15–200 kW, many of the same type	Artesis e-MCM or an AMT Pro route
Submersible / inaccessible pump	ESA (vibration is impractical)
Gearbox after the motor	Vibration on the gearbox plus ESA on the motor
Programme from scratch, limited budget	Start with AMT Pro, then e-MCM on the critical machines

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A combined strategy (the KEG TRK recommendation)

The optimal programme at a large power site is not "either / or":

1. Critical rotating machines (turbines, large fans) — Bently Nevada.
2. The motor fleet — Artesis ESA.
3. Steam leaks, steam traps, bearings — SDT ultrasound.

The integration is described in "Vibration + ultrasound + electrical monitoring" and in the mining + CHP rollout case.

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Conclusion

• Vibration is the gold standard for large rotating equipment with a sensor infrastructure.
• MCSA is a simplified screening; on critical CHP pumps it is often not enough.
• Artesis ESA offers the best balance of coverage and cost for the motors of auxiliary systems.

Next step: 5 typical faults ESA finds in 7 minutes or a 90-day e-MCM pilot.