---
title: "Remedial strategies for energy coupling"
subject: "Instrumentation II"
chapter: 6
key: "semester_5/instrumentation_ii:energy-coupling-remedies"
source: https://www.bctengineer.com/q/semester_5/instrumentation_ii/energy-coupling-remedies
site: BCT Engineering
---

# Remedial strategies for energy coupling

Instrumentation II · Chapter 6: Grounding And Shielding

- Asked in: 2072 Chaitra, 4 marks
- Answer checked by Claude Sonnet 5.5 on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/instrumentation_ii/energy-coupling-remedies
- Whole chapter: https://www.bctengineer.com/md/semester_5/instrumentation_ii/chapter-6

## Question

Explain the remedial strategies for various energy coupling mechanisms.

## Short answer

Conductive coupling is reduced by star grounding, decoupling capacitors, and isolation. Capacitive coupling is reduced by increasing distance, using grounded shields, and lowering receiver impedance. Inductive coupling is reduced by minimizing loop areas, using twisted pairs, and magnetic shielding. Radiated coupling is countered with metal enclosures, filtering, and short leads.

## Answer

Remedies depend on the coupling mechanism:

#### Conductive coupling
- Separate power/ground returns, use star grounding, and reduce common impedance (wide traces, planes).
- Decouple with capacitors; use LC/ferrite filters on power lines.
- Isolate with transformers or opto-couplers.

#### Capacitive coupling
- Increase the distance between conductors and reduce parallel run length.
- Use a grounded electrostatic shield between source and receiver.
- Lower the receiver impedance (a smaller resistor to ground).
- Reduce dV/dt of the source (slower edges, series resistor, snubber).
- Use balanced (differential) lines.

#### Inductive coupling
- Reduce loop areas of both source and victim; use twisted pairs (adjacent loops cancel).
- Increase distance, orient loops at right angles.
- Use magnetic shields (high-permeability material) and shielded cables with return through shield.
- Reduce di/dt of the source.

#### Radiated (EM) coupling
- Enclose the source or victim in a grounded metal shield; filter all the entering lines.
- Reduce antenna lengths, use short leads, and ground the shield at both ends (at high frequency).
- Increase separation, use ferrite beads and slow down edges.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. Which remedy suits conductive (common-impedance) coupling?
   A. Magnetic shielding with mu-metal
   B. Twisting the wires together only
   C. Star grounding, separate returns and isolation by transformers or opto-couplers
   D. Moving the receiver farther away in free space
   Answer: C. Conductive coupling arises from shared wires, so separate returns, decoupling and isolation break it. (Key point: Conductive coupling remedy)

2. How does lowering the receiver impedance help against capacitive coupling?
   A. It increases the stray capacitance
   B. Noise voltage V = R C dV/dt falls because R is smaller
   C. It increases the source dV/dt
   D. It makes the shield unnecessary because it blocks flux
   Answer: B. The noise current through C produces less voltage across a smaller receiver resistor. (Key point: Capacitive remedy: impedance)

3. Which technique reduces inductive coupling?
   A. Reduce loop areas and use twisted pairs so adjacent loops cancel
   B. Increase the loop area to spread the flux
   C. Raise the receiver impedance
   D. Use a thin foil electrostatic shield only
   Answer: A. Smaller loops link less flux, and twisting makes induced voltages in adjacent loops cancel. (Key point: Inductive remedy)

4. Which is a remedy for radiated (EM) coupling?
   A. Longer leads acting as antennas
   B. Faster clock edges
   C. Removing all shields
   D. Grounded metal enclosure, filtering entering lines, short leads and ferrite beads
   Answer: D. Enclosure and filtering stop fields and conducted entry; short leads reduce antenna pickup. (Key point: Radiated coupling remedy)

## Related in Instrumentation II

- [Types of noise coupling mechanisms](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Anc-types) — Instrumentation II, chapter 6, asked 3×
- [Noise coupling mechanisms with pseudo impedance](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Anc-pseudo-impedance) — Instrumentation II, chapter 6
- [Energy coupling; capacitive coupling and remedies](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Acapacitive-coupling-remedies) — Instrumentation II, chapter 6
- [Filtering for conductive noise coupling](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aconductive-noise-filtering) — Instrumentation II, chapter 6, asked 2×

## Related in other subjects

- [Kyoto Protocol flexibility mechanisms](https://www.bctengineer.com/question.md?key=semester_7%2Fenergy_environment_and_society%3Akyoto-flexibility-mechanisms) — Energy Environment and Society, chapter 2