How to avoid costly rework in fiber projects

Unlike traditional single-core fibre, MCF houses multiple independent cores within a single strand, multiplying data-carrying capacity without the need for new ducts or expanded infrastructure. For industries where speed, scale, and resilience are critical, from telecoms and AI to healthcare and smart manufacturing, MCF is setting a new standard. But capacity is only half the story. Deploying MCF requires specialist expertise, from precision splicing and rotational alignment to advanced OTDR testing. With years of experience in next-generation fibre deployments, including Hollow Core Fibre, our engineers and fibre school training programs are trusted by leading operators to deliver complex solutions safely and effectively. The benefits of MCF are clear: - Massive capacity gains without disruptive civil works - Improved efficiency through reduced hardware and power consumption - Enhanced performance for quantum and high-security applications - A truly future-proof foundation for exponential data growth As we head to Connected Britain this month, we’re excited to showcase how NPS is helping clients design, trial, and scale Multi-Core Fibre networks that are ready for tomorrow’s digital demands. 👉 Let’s connect at the event and talk about how Multi-Core Fibre or one of our other services can transform your network. https://lnkd.in/eUuXeHpG #ConnectedBritain #MultiCoreFibre #FibreNewtorks

Know your Splice, Know your process, be the #1 choice. We're here to assist. ○ Minimizing Signal Loss: The primary goal of splicing is to create a seamless, low-loss connection. Every decibel (dB) of signal loss, or attenuation, can degrade network performance, leading to slower speeds, data errors, and a shorter transmission distance. An efficient splicing process, which includes proper fiber preparation and precise cleaving, is crucial for achieving minimal signal loss and ensuring the network operates at its maximum capacity. ○ Enhancing Network Reliability: A poorly executed splice is a weak point in the network, more susceptible to failure from environmental factors like moisture and temperature changes. High-quality, durable splices reduce the need for frequent repairs and maintenance, preventing costly downtime and ensuring a robust and reliable network for customers. ○ Increasing Productivity and Cost-Efficiency: Speed and precision in splicing directly impact project timelines. Faster, more efficient splicing means technicians can complete jobs quicker, allowing them to move on to the next task sooner. This not only increases overall productivity but also reduces labor costs and the potential for expensive re-work caused by faulty splices.

Pilot Wire Protection – Still Relevant in the Digital Protection Era? In modern substations, we often talk about IEC 61850, fiber optics, and numerical relays. But one scheme that has quietly protected feeders and transformers for decades is the Pilot Wire Protection Scheme. What is it? Pilot wire protection uses a pair of dedicated pilot conductors to connect relays at both ends of a line. These relays continuously exchange information and operate on a differential principle. If a fault occurs within the protected zone, both ends trip almost instantaneously. 🔊Technical Edge:- High sensitivity → detects even low-level internal faults. Fast tripping (20–40 ms) → improves system stability. Selective → trips only the faulted section, avoiding unnecessary outages. Works with balanced voltage or balanced current schemes (depending on relay design). 🏭Applications in Industry:- 11kV / 33kV underground feeders Transformer protection (especially between HV & LV sides) Short transmission lines where dedicated pilot cores are available ⚡ Challenges Today: Requires reliable pilot cables — insulation failure or induced voltage can cause misoperations. Limited distance coverage (typically 15–20 km). Being replaced by communication-assisted distance / differential schemes using PLCC, microwave, or fiber. ✨ Yet, despite modern alternatives, many utilities still trust pilot wire protection for its simplicity, proven reliability, and speed. 👉 Engineers, what’s your view? Do you think pilot wire schemes will remain in niche use, or should we phase them out completely in favor of modern digital protection? #PowerSystems #ProtectionEngineering #NumericalRelays #PilotWire #Substation #ElectricalEngineering

Getting fiber right from the start is critical because design and installation mistakes are expensive to fix and permanently limit performance. Proper planning, splicing, and testing ensure low loss, high reliability, and a backbone that can scale for decades without costly rebuilds. Let's quickly delve into why this is important: 1. Design precision: Fiber networks need careful planning of routes, splice points, and terminations. A sloppy start leads to high loss, weak signals, and unreliable links. 2. Capacity planning: Choosing the right fiber type, core count, and topology at the beginning makes it easier to scale without ripping out existing infrastructure. 3. Splicing and installation quality: Poor handling, bending, or dirty splices permanently reduce performance. Unlike copper, fiber doesn’t tolerate errors well. 4. Testing and certification: Proper acceptance testing (OTDR, power meter, inspection) ensures the network can carry high bandwidth now and in the future. Skipping this creates hidden problems that only appear under heavy load. 5. Cost of mistakes: Fixing a bad fiber build often means redigging trenches, repulling cables, or resplicing much more expensive than doing it right from the start. 6. Future scalability: With proper design, a fiber backbone can support decades of growth (DWDM, higher transmission speeds) without replacement. A poor start locks you into limits.

When to use Core Balance Current Transformer (CBCT) vs residual (summation) CTs for Earth Fault Protection : Core Balance CT (CBCT / Zero-Sequence CT) • Measures the true residual (I0 = Ia+Ib+Ic) by enclosing all live conductors (and neutral if present) through one core. • Immune to CT mismatch and unequal saturation of individual phase CTs. • Best for sensitive earth-fault (SEF) elements with very low pickup (typically <5–10% of CT secondary rating, e.g., <5 A on 5 A CTs). • Strongly recommended for: • MV/LV feeder SEF (50N/51N with low pickup). • Motor/cable feeders with small charging/unbalance currents. • LV earth-leakage/ground-fault relays (ZCTs in MCCs/switchboards). • Directional earth-fault protection in compensated or resistance-earthed networks. • Simple, accurate, and avoids “spill current” nuisance trips. Residual / Summation of Phase CTs (Holmgreen Connection) • Obtains zero-sequence current by adding the three phase CT secondary outputs (either wired or in relay software). • Economical: re-uses existing CTs, no extra CBCT required. • Acceptable for non-sensitive earth-fault elements with moderate pickup (≥10–20% of CT secondary rating). • Adequate for feeder or transformer earth-fault time-overcurrent (51N/50N) where grading margins are generous. • Limitation: Sensitive to CT ratio error, unequal saturation, and wiring errors → may cause false or missed trips, especially at low fault current. • Needs identical CT ratios/classes and correct polarity wiring; CT-circuit supervision is recommended. Special Case: Restricted Earth Fault (REF / 64G) • High-impedance REF requires special class PX CTs with defined knee-point, excitation, resistance, and low leakage reactance. • CBCT or residual methods are not interchangeable here—the scheme dictates CT specs. • Low-impedance REF and zero-sequence differential schemes also require careful CT selection and relay supervision. Standards & Guidance • IEC 61869-2: CT performance classes (P, PR, PX) → defines requirements, not connection method. • IEC 60255-151 / IEEE C37.112: Accuracy and inverse-time earth-fault element performance → both CBCT and residual acceptable if accuracy maintained. • Utility & vendor guides: Consistently recommend CBCT for sensitive EF, residual only for non-sensitive applications. Strong Recommendation (Best Practice) • Use CBCT whenever high sensitivity or high dependability is required (SEF, LV leakage, compensated networks). • Use residual summation only where sensitivity is moderate and CTs are well matched (typical feeder/transformer 51N protection). • For REF/differential EF schemes, follow the scheme’s required class PX CT specs. ✅ In practice: CBCT = precise and reliable for sensitive protection; residual = economical but limited to non-sensitive use. International standards don’t prescribe one method but require CT and relay performance; the consensus is CBCT is strongly recommended wherever feasible.

𝐓𝐡𝐞 𝐈𝐧𝐫𝐮𝐬𝐡 𝐂𝐮𝐫𝐫𝐞𝐧𝐭 𝐃𝐢𝐥𝐞𝐦𝐦𝐚 One of the trickiest challenges in transformer protection is inrush current. During energization, transformers can draw up to 10× their rated current. To a protection system, that looks a lot like a short circuit. But it’s not — it’s a normal phenomenon. If relays can’t tell the difference, you end up with nuisance tripping — shutting down healthy equipment and eroding trust in the system. To solve this, engineers use: - Second-harmonic restraint → inrush has distinctive harmonics - Digital waveform analysis → pattern recognition in real-time - Adaptive relay algorithms → filtering logic that distinguishes conditions This is where protection engineering evolves from just “measuring current” to understanding behavior. 🔍 My takeaway: The best protection systems don’t just act — they interpret. 👉 Have you faced inrush trips in your network? What method worked best for you? #SmartGrid #RelayEngineering #ElectricalReliability #LearningJourney

⚡Episode 3.5 Power Transformer Turns Ratio (TTR) Test 🎯 Purpose To verify that the actual winding ratio (HV:LV turns) matches the design/nameplate ratio. To ensure correct vector group and polarity. To confirm tap-changer correctness across all tap positions. This test is critical before energization — a wrong ratio or vector group can cause severe circulating currents or parallel operation failure. Test Connections Equipment: Turns Ratio Tester (TTR) (e.g., Megger TTR, DV Power TRT, Omicron CPC100 with TTR module). Wiring Setup: 1. Connect the H terminal of TTR kit to HV bushing terminals of the transformer. 2. Connect the X terminal of the kit to LV bushing terminals. 3. If a tertiary (Δ) winding is present, connect accordingly to verify vector group. 4. Ensure transformer is isolated and discharged before connection. Principle: TTR kit applies a low AC voltage (~80–100 V) to one winding (usually HV) and measures the induced voltage on LV. Ratio = (Applied Voltage / Induced Voltage). Procedure 1. Select the tap position (start from first tap). 2. Apply test voltage through TTR. 3. Record: Ratio (HV/LV) Phase angle error Deviation from nameplate 4. Repeat for middle tap and last tap (plus all in between for OLTC). 5. Compare readings with nameplate ratio and factory test report. Acceptable Readings (IEC / IEEE Standards) Ratio Error Tolerance: ±0.5% (IEC 60076 / IEEE C57). Phase Angle Error: should be < 40 minutes. Vector Group: must match nameplate (e.g., Dyn11, YNd1). If deviation exceeds limits → OLTC problem, wrong winding connection, or shorted turns. Results on Tap Positions 1️⃣ First Tap (Max Tap / Highest Voltage Tap) HV turns are maximum → ratio is highest. Induced LV voltage is lowest for a given applied HV. Ratio error should still be within ±0.5%. 2️⃣ Middle Tap (Nominal Tap) This is the reference point. Ratio must closely match nameplate ratio. Used for base comparison across taps. 3️⃣ Last Tap (Min Tap / Lowest Voltage Tap) HV turns are minimum → ratio is lowest. LV induced voltage is highest. Current in LV winding will be slightly higher at this tap when energized, but for TTR test (low voltage applied), only the ratio matters. ⚡ Important Field Notes Symmetry: All three phases must show nearly identical ratio values; large deviation in one phase suggests winding deformation or OLTC issue. OLTC Jumps: If the ratio suddenly shifts at a particular tap, the OLTC diverter switch is faulty. Vector Group Check: TTR kits can automatically detect vector group; mismatches are often due to wrong bushing labeling or internal misconnection. ✅ Summary Connect TTR kit → HV side (H terminals), LV side (X terminals). Measure ratio at 1st, middle, and last taps. International standard: ratio error ≤ ±0.5%. Expect: Highest ratio at first tap Nominal ratio at middle tap Lowest ratio at last tap Abnormal readings → suspect OLTC, winding, or vector group issues.

For transformer differential protection to remain stable, the "CT Star Point Earthing" setting must be uniform for all windings (typically all "TOWARDS TRANSFORMER"). An inconsistent setting between windings or a mismatch between a setting and the physical installation will cause the software setup of a numerical differential relay to misinterpret the currents and trip for normal operation. This setting is a key part of establishing the relay's common reference point and must be verified meticulously for every CT input specially for Transformer Differential Protection (87T), Reactor Differential Protection. For a typical two-winding transformer (HV and LV sides) and hints at a third, neutral CT below the expected cases: A. The Ideal Case: 1- Configuration: The "CT Star Point Earthing" setting for both the HV and LV sides is set to "TOWARDS TRANSFORMER". 2- Status: IDEAL 3- Action: NONE. This consistent configuration ensures the relay's internal logic correctly processes the phase relationship between the HV and LV currents for the differential algorithm. B. Example 1 of a Wrong Case: Inconsistent Software Settings 1- Error: The settings are inconsistent. The LV side is correctly set to "TOWARDS TRANSFORMER", but the HV side is incorrectly set to "TOWARDS BUSBAR". 2- Consequence: The relay will interpret the current from the HV side as inverted relative to the LV side. This will cause it to calculate a large false differential current during normal load or external faults, leading to a mal-operation and trip. 3- Corrective Action: The incorrect setting on the HV side must be corrected. The "CT star point earthing" setting for the HV side shall be changed to "TOWARDS TRANSFORMER" to match the LV side and the standard scheme. C. Example 2 of a Wrong Case: Software-Physical Mismatch 1- Error: There is a mismatch between the physical installation and the software setting on the HV side. The CT is physically installed with its star point towards the busbar, but the relay setting is "TOWARDS TRANSFORMER". 2- Consequence: The relay receives a current signal that is inverted from what its configuration expects. This will severely distort the differential calculation and guarantee mal-operation. 3- Corrective Action: This requires a physical correction. The HV CT must be reoriented or rewired so that its star point is physically towards the transformer, thus matching the software setting. Alternatively, the physical installation could be left alone and the software settings for all windings could be flipped (to "TOWARDS BUSBAR"), but this is non-standard and must be approved by the Protection Engineering Department (PED). D. Implied Complexity: The Neutral CT The text mentions a "Neutral CT" with a setting of "TOWARDS BUSBAR". This highlights that for transformers with neutral-side CTs, the same rule applies: the setting must be chosen to be consistent with the overall scheme and the physical installation, or the relay will see an imbalance.

Constructing a fiber optic network involves several key phases: field data collection, make-ready engineering, installation, and rigorous quality testing. Each phase is crucial for a high-performance network. Read the full article here: https://lnkd.in/g63iV-xG #aimifiber #FiberOpticNetwork #QualityTesting #TelecomSolutions

One small mistake in power system design can trigger massive downtime. Are you confident your system is protected? - The key to preventing costly outages isn't just equipment—it's mastering coordination and protection strategies that keep operations running seamlessly. - For example, this training dives deep into fault analysis and relay coordination, helping engineers design systems that minimize risk and ensure safety across HV and MV networks. Businesses that apply these methods achieve fewer interruptions, safer operations, and stronger compliance. - If you or your team design, operate, or maintain power systems, this is knowledge you can't afford to miss. #PowerSystems #EngineeringTraining #GridReliability