# Latest **URL:** https://forumautomation.com/latest.md [Latest](https://forumautomation.com/latest.md) · [Categories](https://forumautomation.com/categories.md) · [Tags](https://forumautomation.com/tags.md) --- ## [What is hysteresis in control valves?](https://forumautomation.com/t/what-is-hysteresis-in-control-valves/14486)
**Author:** [@Instrument\_Engineer](https://forumautomation.com/u/Instrument_Engineer)\ **Replies:** 1\ **Last updated:** [October 30, 2026, 3:52pm UTC](https://forumautomation.com/t/what-is-hysteresis-in-control-valves/14486 "2026-10-30T15:52:14Z")
\*\*What is hysteresis in control valves?\*\* --- ## [What is the difference between ex-e and ex-d protection?](https://forumautomation.com/t/what-is-the-difference-between-ex-e-and-ex-d-protection/14560)
**Author:** [@Instrument\_Engineer](https://forumautomation.com/u/Instrument_Engineer)\ **Replies:** 1\ **Last updated:** [October 30, 2026, 3:50pm UTC](https://forumautomation.com/t/what-is-the-difference-between-ex-e-and-ex-d-protection/14560 "2026-10-30T15:50:14Z")
What is the difference between ex-e and ex-d protection? --- ## [What is the difference between fat and fwt?](https://forumautomation.com/t/what-is-the-difference-between-fat-and-fwt/14559)
**Author:** [@Instrument\_Engineer](https://forumautomation.com/u/Instrument_Engineer)\ **Replies:** 1\ **Last updated:** [October 30, 2026, 3:48pm UTC](https://forumautomation.com/t/what-is-the-difference-between-fat-and-fwt/14559 "2026-10-30T15:48:03Z")
What is the difference between fat and fwt? --- ## [Star Topology in Substation SCADA Systems](https://forumautomation.com/t/star-topology-in-substation-scada-systems/13438)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [August 11, 2025, 12:25pm UTC](https://forumautomation.com/t/star-topology-in-substation-scada-systems/13438 "2025-08-11T12:25:28Z")
Star Topology in Substation SCADA Systems A star topology is a network design in which all devices (such as IEDs, RTUs, and HMIs) are connected to a single node (or) switch. In substation SCADA systems, the central poi… --- ## [How does a 132/33 kV Step-Down Substation operate?](https://forumautomation.com/t/how-does-a-132-33-kv-step-down-substation-operate/14563)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 30, 2026, 2:02pm UTC](https://forumautomation.com/t/how-does-a-132-33-kv-step-down-substation-operate/14563 "2026-10-30T14:02:37Z")
How does a 132/33 kV Step-Down Substation operate? A 132/33 kV step-down substation receives high-voltage electrical power from the 132 kV transmission network, reduces the voltage to 33 kV through a power transformer, a… --- ## [Star-Delta Starter with PLC Control: Motor Starting and Control Logic](https://forumautomation.com/t/star-delta-starter-with-plc-control-motor-starting-and-control-logic/14562)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 30, 2026, 1:50pm UTC](https://forumautomation.com/t/star-delta-starter-with-plc-control-motor-starting-and-control-logic/14562 "2026-10-30T13:50:18Z")
Understand the working principle of a PLC-controlled Star-Delta starter used for three-phase squirrel-cage induction motors. This motor starting method reduces the initial line current by connecting the motor windings in… --- ## [What is ATEX and EX classification?](https://forumautomation.com/t/what-is-atex-and-ex-classification/14561)
**Author:** [@Instrument\_Engineer](https://forumautomation.com/u/Instrument_Engineer)\ **Replies:** 0\ **Last updated:** [October 30, 2026, 1:19pm UTC](https://forumautomation.com/t/what-is-atex-and-ex-classification/14561 "2026-10-30T13:19:15Z")
What is ATEX and EX classification? --- ## [What is the first step in diagnosing a problem with PLC inputs?](https://forumautomation.com/t/what-is-the-first-step-in-diagnosing-a-problem-with-plc-inputs/14558)
**Author:** [@Instrument\_Engineer](https://forumautomation.com/u/Instrument_Engineer)\ **Replies:** 0\ **Last updated:** [October 30, 2026, 1:15pm UTC](https://forumautomation.com/t/what-is-the-first-step-in-diagnosing-a-problem-with-plc-inputs/14558 "2026-10-30T13:15:09Z")
What is the first step in diagnosing a problem with PLC inputs? --- ## [Busbar Differential Protection (87B) in Substations](https://forumautomation.com/t/busbar-differential-protection-87b-in-substations/14555)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 30, 2026, 9:08am UTC](https://forumautomation.com/t/busbar-differential-protection-87b-in-substations/14555 "2026-10-30T09:08:24Z")
Busbar differential protection (ANSI 87B) is a high-speed protection scheme used to detect and isolate internal faults within a defined substation busbar zone. It operates by comparing the vector sum of CT secondary curr… --- ## [What is Shielded Cables and what are the types?](https://forumautomation.com/t/what-is-shielded-cables-and-what-are-the-types/9736)
**Author:** [@Ajmal\_ismail](https://forumautomation.com/u/Ajmal_ismail)\ **Replies:** 0\ **Last updated:** [August 13, 2021, 12:04pm UTC](https://forumautomation.com/t/what-is-shielded-cables-and-what-are-the-types/9736 "2021-08-13T12:04:00Z")
Shielded cables Shielded cables are also called screened cables. Shield cables are electrical cables made up of an insulating conductor surrounded by a common conductor layer. Shielded cables are thicker and more rig… --- ## [How to Troubleshoot Electrical Faults: Causes and Solutions](https://forumautomation.com/t/how-to-troubleshoot-electrical-faults-causes-and-solutions/14554)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 29, 2026, 3:36pm UTC](https://forumautomation.com/t/how-to-troubleshoot-electrical-faults-causes-and-solutions/14554 "2026-10-29T15:36:18Z")
Electrical Fault Diagnosis and Troubleshooting Electrical fault troubleshooting involves identifying, testing, and correcting electrical problems in power distribution systems, control panels, motors, and industrial equi… --- ## [What is a Voltage Sensor? Types, Working Principle and Applications](https://forumautomation.com/t/what-is-a-voltage-sensor-types-working-principle-and-applications/14553)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 29, 2026, 3:27pm UTC](https://forumautomation.com/t/what-is-a-voltage-sensor-types-working-principle-and-applications/14553 "2026-10-29T15:27:44Z")
What Is a Voltage Sensor? Types, Working Principle, and Applications What Is a Voltage Sensor? A voltage sensor is an electrical measurement device used to detect, monitor, and measure voltage levels in AC and DC circuit… --- ## [Why is Hipot Testing important for 11 kV Cables?](https://forumautomation.com/t/why-is-hipot-testing-important-for-11-kv-cables/13565)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [September 23, 2025, 12:22pm UTC](https://forumautomation.com/t/why-is-hipot-testing-important-for-11-kv-cables/13565 "2025-09-23T12:22:50Z")
Why is Hipot Testing important for 11 kV Cables? Hipot Test The Hipot (High Potential) Test is an essential diagnostic test that determines the insulation strength of the high-voltage cables & equipment. For an 11 k… --- ## [Three-Phase Motor Power and Control Circuit](https://forumautomation.com/t/three-phase-motor-power-and-control-circuit/14551)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 28, 2026, 3:16pm UTC](https://forumautomation.com/t/three-phase-motor-power-and-control-circuit/14551 "2026-10-28T15:16:57Z")
Three-Phase Motor Power and Control Circuit A three-phase motor control system integrates the power circuit, control circuit, and auxiliary DC supply to provide reliable motor operation, electrical protection, and operat… --- ## [Adjustable Voltage and Current Protection Relay](https://forumautomation.com/t/adjustable-voltage-and-current-protection-relay/14550)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 28, 2026, 2:11pm UTC](https://forumautomation.com/t/adjustable-voltage-and-current-protection-relay/14550 "2026-10-28T14:11:27Z")
Adjustable Voltage and Current Protection Relay A 63 A adjustable voltage and current protection relay continuously monitors supply voltage and load current to help protect electrical equipment against overvoltage, under… --- ## [Which protective device detects gas accumulation caused by internal faults in a conservator-type oil-immersed transformer?](https://forumautomation.com/t/which-protective-device-detects-gas-accumulation-caused-by-internal-faults-in-a-conservator-type-oil-immersed-transformer/14547)
**Author:** [@TSRS](https://forumautomation.com/u/TSRS)\ **Replies:** 1\ **Last updated:** [October 27, 2026, 1:21pm UTC](https://forumautomation.com/t/which-protective-device-detects-gas-accumulation-caused-by-internal-faults-in-a-conservator-type-oil-immersed-transformer/14547 "2026-10-27T13:21:36Z")
Which protective device detects gas accumulation caused by internal faults in a conservator-type oil-immersed transformer? --- ## [POWER TRANSFORMER PROTECTION](https://forumautomation.com/t/power-transformer-protection/14548)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 27, 2026, 1:19pm UTC](https://forumautomation.com/t/power-transformer-protection/14548 "2026-10-27T13:19:57Z")
Understanding transformer protection schemes is essential for electrical engineers, substation engineers, and maintenance technicians. Key Power Transformer Protection Devices: Differential Protection (87T): Detects i… --- ## [Electrical Cable Sizing: Formulas, Calculations and Engineering Considerations](https://forumautomation.com/t/electrical-cable-sizing-formulas-calculations-and-engineering-considerations/14546)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 27, 2026, 1:00pm UTC](https://forumautomation.com/t/electrical-cable-sizing-formulas-calculations-and-engineering-considerations/14546 "2026-10-27T13:00:22Z")
Electrical Cable Sizing Proper electrical cable sizing is essential for safe and reliable power distribution. An undersized conductor can lead to excessive temperature rise, voltage drop, insulation deterioration, and po… --- ## [USAGE OF RECLOSERS OVER POWER DISTRIBUTION SYSTEM](https://forumautomation.com/t/usage-of-reclosers-over-power-distribution-system/6257)
**Author:** [@Ashlin.aj](https://forumautomation.com/u/Ashlin.aj)\ **Replies:** 0\ **Last updated:** [April 16, 2019, 5:32pm UTC](https://forumautomation.com/t/usage-of-reclosers-over-power-distribution-system/6257 "2019-04-16T17:32:07Z")
USAGE OF RECLOSERS OVER POWER DISTRIBUTION SYSTEM Reclosers are actually circuit breakers and its prime goal is to provide electric power continuously without any distribution problems it senses and interr… --- ## [LV/MV Switchgear Testing and Commissioning](https://forumautomation.com/t/lv-mv-switchgear-testing-and-commissioning/14543)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 26, 2026, 4:21pm UTC](https://forumautomation.com/t/lv-mv-switchgear-testing-and-commissioning/14543 "2026-10-26T16:21:35Z")
LV/MV Switchgear Testing and Commissioning Electrical installation is only the first step toward a reliable power system. Proper testing and commissioning are essential to verify the operational integrity, electrical saf… --- ## [IR Value Testing of Power Transformers](https://forumautomation.com/t/ir-value-testing-of-power-transformers/14542)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 26, 2026, 4:07pm UTC](https://forumautomation.com/t/ir-value-testing-of-power-transformers/14542 "2026-10-26T16:07:50Z")
IR Value Testing of Power Transformers Insulation Resistance (IR) testing is a critical diagnostic procedure used to assess the insulation condition of power transformers before commissioning and during maintenance. U… --- ## [What is difference between ELR and EFR.....?](https://forumautomation.com/t/what-is-difference-between-elr-and-efr/173)
**Author:** [@automate](https://forumautomation.com/u/automate)\ **Replies:** 1\ **Last updated:** [November 29, 2014, 7:23am UTC](https://forumautomation.com/t/what-is-difference-between-elr-and-efr/173 "2014-11-29T07:23:00Z")
What is the difference between ELR and EFR and how they can be selected for different applications…? --- ## [Transformer Turns Ratio (TTR) Testing](https://forumautomation.com/t/transformer-turns-ratio-ttr-testing/14540)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 25, 2026, 7:12am UTC](https://forumautomation.com/t/transformer-turns-ratio-ttr-testing/14540 "2026-10-25T07:12:45Z")
Transformer Turns Ratio (TTR) Testing Transformer Turns Ratio (TTR) testing is an essential diagnostic test used to verify the turns ratio of power and distribution transformers. It compares the measured voltage ratio wi… --- ## [Capacitive Charging Current in Transmission Lines: Causes, Effects, and Control](https://forumautomation.com/t/capacitive-charging-current-in-transmission-lines-causes-effects-and-control/14539)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 25, 2026, 6:32am UTC](https://forumautomation.com/t/capacitive-charging-current-in-transmission-lines-causes-effects-and-control/14539 "2026-10-25T06:32:52Z")
Capacitive Charging Current in Transmission Lines: Causes, Effects, and Control Capacitive charging current is the leading current drawn by the distributed capacitance of an AC transmission line, even under no-load condi… --- ## [Why are high voltage cables more compact than low voltage cables?](https://forumautomation.com/t/why-are-high-voltage-cables-more-compact-than-low-voltage-cables/11443)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [August 28, 2023, 3:50pm UTC](https://forumautomation.com/t/why-are-high-voltage-cables-more-compact-than-low-voltage-cables/11443 "2023-08-28T15:50:51Z")
Due to a number of engineering factors and principles about electrical transmission and insulation, high voltage cables frequently have smaller diameters than low voltage cables. These are some reasoning for why it is so… --- ## [Essential Protection Settings of Air Circuit Breaker (ACB)](https://forumautomation.com/t/essential-protection-settings-of-air-circuit-breaker-acb/14535)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 23, 2026, 2:31pm UTC](https://forumautomation.com/t/essential-protection-settings-of-air-circuit-breaker-acb/14535 "2026-10-23T14:31:34Z")
Essential Protection Settings of Air Circuit Breaker (ACB) An Air Circuit Breaker (ACB) is a critical protection device in low-voltage power distribution systems. Proper protection settings help ensure reliable fault cle… --- ## [LT Panel Fault Codes and Troubleshooting Solutions](https://forumautomation.com/t/lt-panel-fault-codes-and-troubleshooting-solutions/14534)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 23, 2026, 2:27pm UTC](https://forumautomation.com/t/lt-panel-fault-codes-and-troubleshooting-solutions/14534 "2026-10-23T14:27:24Z")
LT Panel Fault Codes and Troubleshooting Solutions Understanding Low Tension (LT) panel fault indications and alarm codes is essential for effective electrical troubleshooting, preventive maintenance, and system reliabil… --- ## [is it possible to draw long time curve or calculate it manually? if it possible, could you please share the calculation?](https://forumautomation.com/t/is-it-possible-to-draw-long-time-curve-or-calculate-it-manually-if-it-possible-could-you-please-share-the-calculation/12855)
**Author:** [@NicholasDeo](https://forumautomation.com/u/NicholasDeo)\ **Replies:** 1\ **Last updated:** [November 26, 2024, 1:49pm UTC](https://forumautomation.com/t/is-it-possible-to-draw-long-time-curve-or-calculate-it-manually-if-it-possible-could-you-please-share-the-calculation/12855 "2024-11-26T13:49:49Z")
is it possible to draw long time curve or calculate it manually? if it possible, could you please share the calculation? --- ## [Why does Transformer Impedance important so much during a Fault?](https://forumautomation.com/t/why-does-transformer-impedance-important-so-much-during-a-fault/14532)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 23, 2026, 1:00pm UTC](https://forumautomation.com/t/why-does-transformer-impedance-important-so-much-during-a-fault/14532 "2026-10-23T13:00:56Z")
Why does Transformer Impedance important so much during a Fault? A transformer may be rated for hundreds of MVA, but its short-circuit impedance plays a critical role in determining the fault current. During a short … --- ## [Why does a Healthy 3-Phase System Have Positive Sequence?](https://forumautomation.com/t/why-does-a-healthy-3-phase-system-have-positive-sequence/14531)
**Author:** [@Rabert](https://forumautomation.com/u/Rabert)\ **Replies:** 0\ **Last updated:** [October 23, 2026, 12:42pm UTC](https://forumautomation.com/t/why-does-a-healthy-3-phase-system-have-positive-sequence/14531 "2026-10-23T12:42:20Z")
Why does a Healthy 3-Phase System Have Positive Sequence? In a balanced three-phase power system, the three phase currents have equal magnitudes, a 120° phase displacement, and the correct phase rotation. This is known a… [Next page](https://forumautomation.com/latest.md?page=1)