Short Answer:

Electromagnetic interference (EMI) negatively affects measurement systems by introducing unwanted signals that can distort, interrupt, or corrupt the actual measured data. EMI may come from nearby electronic devices, power lines, or radio transmitters and can cause serious errors in sensitive instruments.

This interference can lead to incorrect readings, false triggering, reduced accuracy, and unstable outputs. In severe cases, it may damage the system or cause it to fail completely. That is why shielding, grounding, filtering, and proper cable layout are used to protect systems from EMI.

Detailed Explanation:

Effect of electromagnetic interference on measurement systems

In electrical and electronic environments, measurement systems are designed to detect, amplify, and process small or precise electrical signals. These signals can be easily disrupted by electromagnetic interference (EMI), which is the disturbance caused by external electromagnetic fields interacting with sensitive components or circuits.

EMI is a form of noise or unwanted energy that can come from natural or artificial sources and can have major impacts on the performance and reliability of measurement systems.

Sources of EMI:

• Power lines (50/60 Hz hum)
• Electric motors, transformers, and relays
• Switching power supplies and inverters
• Mobile phones, radio transmitters, and wireless devices
• Lightning and electrostatic discharge (natural EMI)

Main effects of EMI on measurement systems:

1. Signal Distortion:
   EMI can enter the measurement circuit and alter the waveform or shape of the actual signal. This results in incorrect readings, especially in analog systems such as voltage or current sensors.
2. Reduced Accuracy:
   Measurement systems are designed to read small voltage or current changes. EMI adds random or patterned noise, making it difficult to isolate the actual signal. This leads to loss of accuracy and measurement uncertainty.
3. False Triggering or Readings:
   Digital systems may misinterpret noise spikes as real signals, leading to false switching, alarms, or wrong values being recorded.
4. Unstable Outputs:
   EMI can make the readings fluctuate continuously instead of giving a stable output, which is especially problematic in data logging, instrumentation, and process control.
5. Communication Errors:
   In systems using data transmission (like serial communication, Ethernet, or CAN), EMI can corrupt data packets, causing communication failure or data loss.
6. System Malfunction or Shutdown:
   Severe EMI can damage internal circuits, reset microcontrollers, or crash software in the system. This may result in complete system failure or require a restart.
7. Long-Term Degradation:
   Continuous EMI exposure can wear out components faster, leading to reduced lifespan and reliability of the equipment.

Sensitive areas affected by EMI:

• Medical devices like ECG or EEG machines
• Industrial process controllers and PLCs
• Scientific and laboratory measurement instruments
• Sensor-based systems in automation
• Automotive electronic systems

Methods to reduce EMI effects:

• Shielded cables and enclosures
• Proper grounding and bonding
• Twisted-pair wiring for signal lines
• Use of EMI filters on power inputs
• Physical separation between power and signal lines

Conclusion:

Electromagnetic interference (EMI) can cause serious problems in measurement systems by distorting signals, reducing accuracy, and even causing system malfunctions. Understanding its effects and applying proper protection techniques like shielding, grounding, and filtering are essential for ensuring accurate, stable, and reliable measurements in electrical and electronic applications.