Quality GE Bently Nevada & E&H Instrument factory

Choosing Between DN2, DN40, DN50 and DN65 in the Promag H 300 Range Four bores of the same series: DN2, DN40, DN50 and DN65, all held in stock. Four sizes of one series now sit in our warehouse: DN2, DN40, DN50 and DN65 Promag H 300 instruments, each configured to a distinct order code. The question we are asked most often is which bore belongs on which line. The short answer is that size follows the flow band, and the flow band follows the duty, not the pipe thread that happens to be available. Duty-based selection BoreOrder codeDuty it is chosen forWhat goes wrong if undersized or oversizedDN2 (1/12 in)5H3B02-AAIBAEAFBAFDCS0BA2Micro-dosing and filling machine feed, a few litres per hourOversized: resolution lost at the bottom of the span, batches trimmed by handDN40 (1-1/2 in)5H3B40-AAIBAEAFBAFDCS0BA2CIP supply and return, product recovery loopsUndersized: cleaning velocity limited by the meter rather than the pumpDN50 (2 in)5H3B50-AAIBAEAFBAFDCS0BA2Batching and main hygienic transferUndersized: batch cycles stretched, pressure consumed by the meterDN65 (2-1/2 in)5H3B65-AAIBAEAFBAFDCS0BA2High-throughput filling, dairy and beverage mainsOversized: poor resolution at low overnight flow Four checks before fixing a bore Minimum and maximum flow: the working band should sit inside the achievable range for that bore, not at its edgesConductivity: 5 microsiemens per centimetre as a rule, about 20 for demineralised waterCleaning regime: temperature and chemical exposure decide whether the PFA liner and the IP69 option are neededStraight run available: about 5 DN upstream and 3 DN downstream, or a vertical riser where space is short What all four share Every size in the range uses the same transmitter platform: 4-20 mA HART, pulse and frequency outputs, up to three I/Os, a backlit display with touch control and WLAN access, and Heartbeat Technology for in-line verification. Measurement error is ±0.5 % of reading ±1 mm/s as standard, with the 0.2 % option available, and all sizes span −20 to +150 degrees Celsius with a PFA liner and 316L electrodes as the standard wetted pair. Standardising a plant on one series The practical benefit of buying four sizes of one family is not the price of any single unit. It is that the parameter set, the spare seals, the grounding rings and the operator training are shared, and a maintenance technician who has commissioned the DN50 can commission the DN2 without a second manual. For projects that need several sizes at once, we can ship them as one consignment and supply the matching connection adapters together. Availability All four order codes are held in stock with a minimum order quantity of one piece, T/T or L/C payment and a 12-month warranty, shipping in three to five working days. Send the line list with medium, temperature and flow band for each point, and we will return a bore recommendation per line before the quotation is issued. Contact our instrumentation team for a bore recommendation and stock confirmation.

Pressure Loss on DN65 Dairy Mains: The Case for a Full-Bore Sensor DN65 (2-1/2 in) Promag H 300 feeding a high-speed filling line. When a dairy or beverage main already runs near its hydraulic limit, every component in the line is a tax on throughput. A measuring point that constricts the bore is the most expensive kind, because the loss is permanent: it is paid on every litre, every shift, for the life of the plant. This is the argument for choosing a full-bore electromagnetic sensor on DN65 duty rather than a device with an internal rotor or a reduced measuring section. What a constriction actually costs Restrictions penalise the line twice. First as head loss, which the pump has to make up in energy. Second as a limit on peak filling rate: when a filler calls for a short high-flow burst, a restrictive meter forces either a lower burst rate or a higher pump pressure, and both options show up in operating cost. Order code 5H3B65-AAIBAEAFBAFDCS0BA2 avoids the trade-off because the measuring tube has the same bore as the pipe. Design pointEffect on the lineFull-bore PFA-lined measuring tubeNo added restriction; pump duty unchanged from the bare pipe caseNo moving partsNothing to wear, nothing to block; cleaning velocity is set by the pumpBidirectional, independent of viscosityRecipe changes do not require recalibration or a new K factorSeries span to 600 m³/hHeadroom for filling peaks without changing the instrument Where the payback appears Pump energy on a continuously running main, which is the largest and most predictable savingFilling rate, where a higher permitted burst shortens the fill cycleProduct loss, because a straight tube drains and cleans more completely than a rotor housingDowntime, because verification can be done in line rather than by removing the sensor Sizing the DN65 correctly The bore should be chosen from the flow band, not from the adjacent pipe thread. A DN65 sensor is normally selected where the working flow sits in the upper part of the DN50 range or above it, and where the sustained rate justifies the larger line. Running a DN65 instrument at a fraction of its span wastes resolution; running a DN50 above its span wastes pressure. Our team will run the numbers from your flow band and product data before quoting. Service details The unit is supplied new in original Endress+Hauser packaging with a 12-month warranty, minimum order one piece, T/T or L/C. Seals, grounding rings and connection adapters are available as separate items. Stock normally ships within three to five working days. Contact our instrumentation team for throughput and sizing calculation.

DN50 Electromagnetic or Mechanical Meter: The Real Differences in Batching DN50 (2 in) Promag H 300: no rotor, no shaft seal, no constriction in the measuring tube. Both instrument types will pass product and produce a number. The difference appears in the second year, when the mechanical meter has worn, the product has changed, and the batch record has to be reconstructed. Below is how the two approaches compare on a typical 2 inch hygienic batching line. CriterionMechanical / turbine meterPromag H 300 DN50Moving partsRotor and bearings in the product pathNone; electromagnetic measurementPressure lossConstriction at the rotor, permanent energy costFull bore, no added restrictionBehaviour with viscous productReading drifts with viscosityIndependent of viscosity, density, pressure, temperatureCleaningRotor housing traps product and slows CIPStraight tube, drains and cleans with the lineWear and recalibrationRecalibration intervals shorten with useNo wear parts; in-line verification availableBatch controlPulse output, needs an external totaliserTotaliser inside the transmitter, up to 3 I/Os What this means on the line The energy argument is easy to underestimate. A restriction of a few tenths of a bar, running three shifts, is paid for continuously by the pump. On a 2 inch line the full-bore design of order code 5H3B50-AAIBAEAFBAFDCS0BA2 removes that cost, and equally removes the dead zone where the rotor housing used to sit, so cleaning chemistry reaches the whole pipe. Where the change is felt first Batch repeatability improves because the zero point no longer shifts after CIPProduct changeovers get shorter: no rotor to flush and no bearing to inspectMaintenance planning simplifies: seals and grounding rings are the only wear items in the loopDiagnostics appear in the control system instead of an operator noticing a slow batch When a mechanical meter still makes sense On clean, low-value, non-hygienic water lines with a stable viscosity and no cleaning cycle, a mechanical device can be the cheaper answer, and we will say so. The crossover point is hygienic duty: food, beverage and life science lines where cleaning validation, product loss and changeover time are part of the cost of ownership. There the electromagnetic sensor is usually the lower-cost option once the first year is over. Technical summary ParameterValueOrder code5H3B50-AAIBAEAFBAFDCS0BA2Nominal diameterDN50 (2 in)Measurement error±0.5 % o.r. ±1 mm/s; 0.2 % optionMedium temperature–20 to +150 °COutputs4-20 mA HART, pulse/frequency, status output The DN50 unit is in stock, minimum order one piece, T/T or L/C, 12-month warranty. Send us the existing meter datasheet and the batch specification, and we will lay the comparison against your actual duty rather than a generic table. Contact our instrumentation team for a side by side selection review.

Documenting CIP and SIP Cycles With a DN40 Promag H 300 DN40 (1-1/2 in) build: the working size for CIP supply and return headers. A cleaning cycle is only validated if someone can show what happened during it: flow, temperature and time, cycle after cycle, without gaps. Temperature is usually recorded by the skid. Flow is where the evidence is thinnest, because many plants infer it from pump curves. A DN40 electromagnetic sensor placed on the supply or return header turns that inference into a recorded value. What the instrument contributes to the validation file A continuous 4-20 mA or pulse signal that can be logged by the skid PLC alongside temperature and conductivityMeasured cleaning velocity, which is the parameter most often assumed rather than demonstratedAn in-line verification function (Heartbeat Technology) that produces a record without removing the sensorA factory calibration record delivered with the instrument, traceable to manufacturer standards The DN40 build, order code and environment Order code 5H3B40-AAIBAEAFBAFDCS0BA2 covers the DN40 (1-1/2 inch) sensor with a PFA liner and stainless steel housing. It spans −20 to +150 degrees Celsius, so the same unit handles chilled rinse water at the start of a cycle and hot caustic later in the same shift, with sterilisation at 150 degrees Celsius and 5 bar for up to 60 minutes inside the series envelope. The hygienic housing is rated up to IP69, which matters in a room where washdown hoses are used daily. ParameterValueNominal diameterDN40 (1-1/2 in)Medium temperature–20 to +150 °CSterilisation150 °C at 5 bar, max. 60 minLiner / electrodesPFA / 1.4435 (316L), Alloy C22, tantalum, platinumIngress protectionIP66/67, hygienic housing up to IP69Hygiene basis3-A and EHEDG design, FDA-compliant wetted materials Placement rules that keep the data honest Install the sensor where the pipe runs full in both cleaning directions, ideally in a vertical riser on the return leg, with the transmitter accessible for the operator who signs the record. Avoid mounting immediately downstream of a valve that throttles, because the resulting profile biases the reading. If the circuit is cleaned in reverse flow, confirm that the configuration is set for bidirectional measurement so the totaliser keeps counting during backflush. Availability Stock units ship within three to five working days, with one piece as the minimum order and a 12-month warranty. Audit documentation, material certificates and connection adapters can be supplied together with the instrument. Share your cleaning regime and skid drawing, and we will confirm the size and the connection before the order is placed. Contact our instrumentation team for stock confirmation, datasheets and hygiene documentation.

Retrofitting a DN2 Filling Line: From Timed Shots to Measured Volume Promag H 300 in DN2 (1/12 in): full-bore PFA liner in a stainless steel hygienic housing. Most small filling machines do not start life with a flowmeter. They start with a timer: open the valve for a fixed number of milliseconds and hope the product temperature, tank head and pump wear stay where they were on commissioning day. The result is overfill on warm product, underfill on cold product, and a quality team that compensates by setting the target high and giving product away. Fitting a DN2 electromagnetic sensor closes that loop. Why the DN2 Promag H 300 fits this duty The sensor is built around a full-bore measuring tube with a PFA liner, so there is no constriction to slow the fill or trap product between batches. Order code 5H3B02-AAIBAEAFBAFDCS0BA2 is the stocked configuration. Because the transmitter is the same platform used on the larger bores of the series, a plant that already runs Promag H instruments does not add a new parameter set or a new spare part family for the small line. Retrofit sequence that avoids downtime Measure the existing dosing line: internal diameter, straight run available, and whether the pipe is stainless or plasticConfirm conductivity, typically 5 microsiemens per centimetre or more, and around 20 for demineralised waterSelect the hygienic connection that matches the existing union, so no welding is required on the product sideWire the pulse output into the existing filler controller and switch the shot from time-based to volume-basedRun three validation fills at low, nominal and high target volume before releasing the line What the retrofit changes in practice Typical beforeTypical afterFill volume set by valve open timeFill volume set by measured volume, with the totaliser in the transmitterShift-to-shift drift as pump wearsDrift removed; the reading does not depend on pressure or viscosityProduct given away to protect against underfillTarget set to the real specification, overfill reducedNo record of what was filledPulse output gives a per-container count for the batch record Points that decide success Keep the tube full at zero flow and allow roughly 5 DN upstream and 3 DN downstream; on very short filling drops, mount the sensor in the vertical run where product cannot drain away from the electrodes. For plastic or lined piping, fit grounding rings as part of the same order. Empty pipe detection should be enabled so the controller does not count air as product at the end of a tank. Stock and support The DN2 unit is held in stock with a minimum order quantity of one piece, T/T or L/C payment terms and a 12-month warranty. Send us the fill volume, cycle time and a photo of the existing dosing line, and we will confirm the connection and the option string before shipment. Contact our instrumentation team for stock confirmation, datasheets and sizing support.

Condenser and Deaerator Dissolved Oxygen Exceedance: Causes and Corrective Actions Dissolved oxygen refers to the oxygen dissolved in water, measured in µg/L. During operation, if the oxygen content in condensate or feedwater exceeds the value specified in the operating procedures, it is considered dissolved oxygen exceedance. The dissolved oxygen in the condenser and deaerator must be kept within limits; once it exceeds them, adjustment should be made immediately. Hazards of Dissolved Oxygen Exceedance Oxygen causes oxidation corrosion of metal equipment such as pipes, valves, feedwater pumps, high- and low-pressure heaters, economizers and water walls, producing rust and impurities. Impurities clog filters and valves, affecting feedwater flow. Impurities deposit on heating surfaces, causing scaling, reducing heat-exchange efficiency and potentially leading to tube-wall bursting. Consumption of deoxygenation chemicals increases, raising unit operating costs. Long-term exceedance seriously threatens the safe and stable operation of the unit. Causes and Treatment: Condenser Dissolved Oxygen Exceedance Check whether outside air leaks into the condenser — inspect condenser vacuum, shaft seal pressure, and whether pumps and valves admit air. Low unit load, low condensate temperature and low ambient temperature make oxygen dissolve into water very easily. Properly increase the sealing water pressure of the condensate pump and adjust the sealing water to trickle evenly onto the condensate pump packing. Check the dissolved oxygen of the chemical makeup water; if it exceeds the limit, contact the chemical department to make adjustments. Causes and Treatment: Deaerator Dissolved Oxygen Exceedance Check whether condensate dissolved oxygen exceeds the limit (same checks as above). Check the opening of the deaerator exhaust-to-atmosphere valve; if too small, open it appropriately. Check whether high-pressure heater drain is normal; a leaking valve can cause oxygen to dissolve into the water. Check whether a large amount of cold water is being supplied to the deaerator — common at low load when boiler slag-cooling water is excessive. Check the deaerator heating steam source; if extraction steam pressure and temperature are low, the water is not heated sufficiently and oxygen is not fully released. Internal structure damage of the deaerator — blocked or fallen nozzles, internal breakage, etc. Large load fluctuation with the deaerator water level too high or too low causes exceedance and incomplete deaeration. Air leaking from the feedwater pump sampling valve — common when the sampling valve is not closed in time during feedwater pump shutdown for maintenance. Summary of Common Causes EquipmentCommon CauseCorrective Action CondenserAir in-leakage, low load / low temperature, uneven sealing waterCheck vacuum and seals, raise sealing water pressure, adjust makeup water DeaeratorSmall atmosphere exhaust opening, low load with low water temperature, leaking drainsOpen exhaust valve, raise heating steam, check drains and internals Feedwater pumpSampling valve admits air after shutdownClose the sampling valve in time Conclusion Condenser and deaerator dissolved oxygen exceedance can lead to unsafe events, so it must be adjusted immediately once detected. In daily operation, the most frequent causes of deaerator dissolved oxygen exceedance are low water temperature at low load, low ambient temperature, uneven adjustment of condenser sealing water, a small deaerator atmosphere exhaust opening, and air admitted through the feedwater pump sampling valve after shutdown. Correctly identifying the cause allows operators to restore dissolved oxygen to within the qualified range quickly and keep the unit running safely.

The Overlooked Accumulator: How a Silent Device Safeguards Turbine Systems Many operating personnel know only that an accumulator exists. Some cannot even tell where it is installed or what it actually does. So why does this device get overlooked? First, unlike pumps, valves and bearings, the accumulator has no temperature, vibration or current monitoring. Second, it simply “stands quietly” — when system pressure is normal, no one notices it is there. Third, operating procedures rarely describe it clearly, and there is little dedicated training on it. In turbine systems, however, the accumulator plays a critical role. It is mainly installed in the hydraulic control oil system (EH oil / governing oil) and the lube oil system. 1. How the Accumulator Works Inside the accumulator, an inert gas (usually nitrogen) is separated from the hydraulic oil by an elastic diaphragm, bladder or piston. Its energy cycle works in two stages: Energy storage: When system pressure rises, hydraulic oil enters the accumulator and compresses the gas. The gas volume shrinks and its pressure increases, so energy is stored in the form of compressed gas. Energy release: When system pressure drops or a large flow is momentarily required, the gas expands and pushes the hydraulic oil back into the system, supplying flow or holding pressure. This is exactly why, after an oil pump stops, the oil pressure does not drop to zero immediately but declines slowly — the accumulator is at work. During operation, if a pump suddenly fails, the accumulator buys operators precious golden time to respond. 2. Main Roles of the Accumulator FunctionDescriptionBenefit Store pressure oil & emergency supplyWhen a sudden leak or short pump failure occurs, the accumulator quickly releases pressure oil to hold oil pressure briefly, ensuring valves and actuators still act.Buys time for operational response Absorb pressure shocks & buffer pulsationPump start/stop and fast valve switching create pressure fluctuation and water-hammer shocks; the accumulator absorbs them and reduces oil pressure pulsation.Protects pipes and pressure components, cuts vibration Maintain system pressure stabilityWhen small amounts of oil are used and pressure drops slightly, the accumulator releases oil to compensate.Stabilizes working pressure, avoids frequent pump cycling and reduces energy consumption Compensate for leakageMinor internal leakage in hydraulic valves and seals slowly lowers pressure over long runs; the accumulator continuously tops up a small amount of oil.Maintains system pressure over time 3. Operation Monitoring and Inspection Monitor whether the EH oil main pipe pressure and the lube oil main pipe pressure are steady, and check for abnormal fluctuation. Inspect the accumulator appearance: leakage, vibration, abnormal noise, and frosting or oil seepage at the charging valve. Conclusion The accumulator is a quiet but indispensable guardian of turbine hydraulic and lube oil systems. Although it is easy to overlook, it stores energy for emergencies, absorbs pressure shocks, stabilizes system pressure and compensates for leakage. Regular monitoring of oil pressure stability and careful visual inspection of the accumulator are simple steps that can prevent unexpected downtime and protect the entire system.

Project Background Vortex flowmeters are a cornerstone of accurate flow measurement across the chemical, petrochemical, water treatment and power generation industries. However, even a well-engineered vortex flowmeter can deliver unreliable readings when it is exposed to adverse installation conditions, electrical interference or insufficient maintenance. This case study summarizes a structured field-troubleshooting program developed for a manufacturing client whose process control and measurement accuracy had been repeatedly disrupted by recurring vortex flowmeter faults. Key Fault Symptoms and Corrective Actions 1. Pipeline Has Flow, but the Vortex Flowmeter Produces No Output or a Blank Display Power supply not connected or voltage out of the operating range: inspect the power supply and confirm that the voltage matches the meter specification. Flow rate too low and below the meter minimum range: increase the flow rate or reselect a flowmeter with a suitable measuring range. Pipeline valve closed or not fully opened: verify and correct the valve position. Signal amplifier board failure: contact after-sales support to repair or replace the amplifier board. 2. No Flow in the Pipeline, but the Meter Still Outputs a Signal Strong electrical or high-frequency interference near the meter: relocate the installation point away from the interference source. Excessive pipeline vibration or a nearby vibration source: reinforce the pipeline or choose a new mounting location. Valve not fully closed: inspect and ensure the valve closes tightly. Amplification gain or trigger sensitivity set too high: adjust the parameters to appropriate values. 3. Unstable Flow Output Electrical interference combined with poor grounding: check the shielded signal cable and amplifier-board fasteners to guarantee solid grounding. Insufficient straight pipe length or a mismatched pipe bore: reinstall according to the manual and select a matching pipe. Pipeline vibration: reinforce the pipeline or relocate the meter. Non-concentric installation, seal gasket problems or disturbing valves upstream/downstream: reinstall the meter or inspect the valves. Fluid not filling the pipe or a gas–liquid two-phase flow: re-select a proper installation point. Foreign objects or wrappings at the meter inlet: remove the meter and clean the inlet. 4. Displayed Flow Does Not Match the Process Flow No real-time temperature/pressure compensation for gas or steam, or incorrect setpoints: add temperature and pressure elements and verify the actual operating conditions. Incorrect installation positions of the temperature and pressure elements: re-select and reinstall the measurement points. 5. Additional Faults and Remedies Sensor damage caused by mechanical impact, over-temperature, over-pressure or corrosion: replace the sensor promptly. Display failure due to poor contact or damage: reconnect or replace the display. Long-term operation without maintenance: implement a scheduled maintenance and inspection program. Quick-Reference Troubleshooting Summary Symptom Likely Root Cause Recommended Action No output with flow present Power, valve or amplifier board Check power, open valve, repair or replace the amplifier Output present without flow Interference, vibration or high gain Relocate, reinforce the pipe, adjust parameters Unstable output Grounding, straight pipe or two-phase flow Fix grounding, reinstall, clean the inlet Reading mismatch Missing compensation or wrong installation Add T/P elements, verify setpoints Results and Client Benefits By applying this systematic diagnostic checklist, the client maintenance team reduced unplanned flowmeter downtime, restored measurement accuracy and extended the service life of its vortex flowmeters. Routine inspection, periodic cleaning of the sensor and rotor surfaces, and timely replacement of worn components proved to be the most effective measures for preventing faults before they affected production. This case demonstrates that reliable vortex flowmeter performance depends not only on correct product selection but also on proper installation, grounding and a disciplined preventive maintenance schedule.

Project Background Accurate measurement of compressed air is essential for energy management, leak detection and cost control in modern production facilities. When an industrial client deployed an E+H mass flowmeter to monitor compressed air consumption, the initial readings were unstable and occasionally inaccurate because the meter had been left with factory defaults intended for liquid service. This case study documents the complete parameter configuration performed to obtain reliable gas flow measurement. Key Parameters Configured for Compressed Air 1. Measurement Unit Settings The mass flow unit (for example kg/h or t/h) and the totalizer unit were set to match the actual application so that operators could read and record consumption consistently with their energy-management system. 2. Range Settings The lower (4 mA) and upper (20 mA) limits of the analog output were configured according to the expected compressed-air flow range, ensuring that measured values are displayed accurately within the calibrated span. 3. Low Flow Cutoff (Optional) To suppress tiny flows and signal noise, a low flow cutoff of approximately 1%–5% of the full range was applied, preventing minor fluctuations from affecting measurement precision. 4. Empty Pipe Detection (EPD) Because compressed air has a very low density, empty pipe detection was switched off for gas measurement. Leaving EPD enabled can cause false alarms and measurement interruptions when the gas density is low. 5. Flow Direction Setting The measuring direction (forward or reverse) was configured according to the actual installation orientation so that the meter correctly identifies the direction of media flow. 6. Density-Related Parameters (Optional) To calculate standard volumetric flow or perform density compensation, the standard-condition air density (about 1.293 kg/m³) was entered and density compensation was enabled. 7. Damping Settings (Optional) The flow damping factor was tuned to the on-site working conditions to smooth the measurement signal and reduce output fluctuation. Configuration Summary Parameter Recommended Setting Purpose Measurement unit kg/h or t/h + totalizer unit Match application and reporting Range (4–20 mA) Lower and upper limits per expected flow Accurate span display Low flow cutoff 1%–5% of full range Remove noise and micro-flows Empty pipe detection Disabled for gas Avoid false alarms Flow direction Forward or reverse per installation Correct flow recognition Air density 1.293 kg/m³ + compensation Standard volumetric flow Damping Tuned to site conditions Smooth the signal Results and Client Benefits After the parameters were configured through the flowmeter's operating interface and companion commissioning software, the client obtained stable, accurate compressed-air measurements, improved the reliability of its energy-monitoring data and gained a clearer picture of air consumption across production lines. These settings confirm an important practice: the exact procedure may vary slightly between models, so consulting the device manual or an E+H technical support specialist ensures the optimum configuration for each application.

Customer Background The turbine-generator is the heart of a thermal power plant, and mechanical quantity instruments are the electrocardiogram that watches it beat. In the thermal instrumentation of a 600 MW-class power plant we support, the Turbine Supervisory Instrumentation (TSI) system continuously monitors shaft relative vibration, bearing absolute vibration, axial displacement, differential expansion, casing expansion, rotor eccentricity, speed / zero speed and key phasor. However, frequent false TSI alarms, drifting readings and unclear maintenance standards troubled the instrumentation team, so they worked with our engineers to rebuild a reliable measurement and maintenance system. Challenge Frequent false TSI alarms that disturbed operators and risked unit trips; Unstable or drifting signals on shaft vibration, axial displacement and expansion channels; Gap voltage moving out of the linear zone, signal loss caused by open or short circuits, and inaccurate readings from contamination, loose brackets and aging sensors; No clear standards-based procedure for installation, overhaul and acceptance of mechanical measurement loops. Solution: A Complete Measurement and Maintenance System Our solution covers the six parameter families of turbine mechanical condition monitoring - vibration, displacement, expansion, speed, eccentricity and key phasor - built on three core sensing technologies: Eddy-current sensors - the workhorse of TSI measurement. Non-contact measurement based on the eddy-current effect with a 0-10 kHz frequency range, resolution down to 0.01 mm and strong resistance to oil contamination. Typical output is -4 V to -20 V DC, with the gap voltage set at the linear midpoint (about -10 V DC for a 200 mV/um, 8 mm probe). They cover shaft vibration, axial displacement, differential expansion, eccentricity, key phasor and speed measurement. LVDT sensors - contact-type displacement sensors for large travels up to 0-80 mm with linearity within ±1% F.S., mainly used for casing expansion and part of differential expansion. TD-2 series thermal expansion sensors provide 4-20 mA retransmission plus local indication. Magnetoelectric velocity sensors - the traditional choice for bearing absolute vibration, rigidly mounted on machined bearing pedestals; modern units may use piezoelectric accelerometers with double integration. Typical 600 MW Unit TSI Configuration Monitoring ItemTypical Configuration Shaft vibration7 bearings x X/Y directions, 14 eddy-current probes Bearing absolute vibration7 magnetoelectric velocity sensors Axial displacement2-3 eddy-current probes (redundant) Differential expansion1-2 eddy-current or LVDT probes per HP/LP side Casing expansion1-2 LVDT sensors Eccentricity / key phasor1 eddy-current probe each Speed / zero speed2-3 sensors (magnetoelectric + eddy-current combination) For sensor selection, the probe coil diameter determines the measuring range: 8 mm probes cover about ±1 mm for shaft vibration, eccentricity and key phasor; 11 mm probes ±2 mm; 14 mm probes ±4 mm for medium axial displacement and differential expansion; 25 mm probes ±6 mm; and 50 mm probes ±12 mm for large expansion measurement. Fault Handling and Maintenance Highlights Following GB/T 34578-2017 and DL/T 1056-2019, we helped the plant establish daily inspection and troubleshooting mechanisms for the five most common fault families: unstable output or drift, abnormal gap voltage jumps, signal loss or constant output, inaccurate readings, and frequent false alarms. Key engineering practices include: Single-end grounding of the shielded cable at the TSI cabinet side only, with the probe side floating to eliminate ground loops; Checking probe coil resistance (about 7.5 Ω ± 0.5 Ω for typical series) to identify open or short circuits; Sealing high-frequency joints with heat-shrink tubing and keeping them insulated and floating as required by DL 5190.4-2019; Setting the zero reference with the thrust disc seated against the thrust bearing, and verifying protection set-points by simulated wear tests; Calibrating sensors every 6-12 months, keeping insulation resistance above 1 MΩ, and maintaining complete technical archives. Outcome After the retrofit, false alarms were eliminated, measured values returned to the trustworthy linear zone, and the plant gained a clear standards-based workflow covering installation, routine inspection, overhaul acceptance and protection logic testing (DL/T 1012-2006, GB/T 11348.2-2012, GB/T 6075). Shaft vibration evaluation is now performed against the A/B zones of the national standards, and every measurement loop truly acts as the sentry of long-term, safe turbine operation. For OEM supply of eddy-current probes, preprocessors, LVDT and velocity sensors, or TSI retrofit and commissioning support, contact our engineering team.