Electrical instrument Condition monitoring using ESA (Electrical Signature Analysis)

What is ESA ( Electrical Signature Analysis)?

Electrical signature analysis (ESA), a powerful technology that can be used into most electro-mechanical equipment to greatly enhance condition diagnostics and prognostics capabilities. ESA does not interfere with the operation of the equipment.

Compared to conventional vibration assessment, the ESA scheme is more effective and accurate but needs access only to electrical wires with input or output energy rather than to the machinery itself.

ESA provides the capability of detecting power supply issues, severe connection problems, airgap faults, rotor faults, electrical and mechanical faults in the motor and driven load, including some bearing faults

How the ESA works?

ESA provides a breakthrough in the ability to detect and quantify mechanical defects and degradations in electro-mechanical equipment and unwanted changes in process conditions.


Time-dependent changes in load and velocity that occur throughout an electro-mechanical scheme will usually cause tiny differences in the electrical reaction of the motor and/or generator. These variations are observed as a change in current (for a motor) or a change in voltage (for a generator).

Fault detection using ESA:

Here is an example for the ESA fault detection for Motor Operated Valves (MOV’s). The primary failure of these machines is the rotor which would overload and melt when limit switches failed.

The rotor bar error signature was found to be distinctive enough not only to be able to rapidly identify the signature, but also to be able to readily apply status scores. Pole Pass Frequency sidebands (P1 and P2) for MOV is given below:

This pole pass frequency graph will be compared with the standard allowable pole pass frequency. If the values exceed the standards, the rotor condition is not good. The result can be a dampening effect on those peaks resulting in the analyst needing to estimate the severity of the fault.

Application of ESA:

  • Large blowers and fans

  • Water & Fuel pumps

  • Air compressor

  • Vacum pumps

  • HAVC equipments

  • Textile production machines

  • Automobile alternators

  • Electric vehicle motor

  • Diesel engine starter motor

  • Large compressor

  • Portable power generator sets

  • Helicopter

  • Variable Speed Drive

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