We offer professional Prospective Short Circuit Current(PSC) services in India compliant with national and international standards.
The Prospective Short Circuit Current(PSC) is the utmost current that could flow between Line and Neutral conductors on a single-phase supply or between Line conductors on a three-phase supply. A PSC test calculates the current that will flow in the event of a short circuit fault between the live conductors. That is, Line and Neutral on a single-phase installation or Line to Line/ Line to Neutral on a three-phase installation.
Prospective Fault Current (PFC) is the common term used for the highest amount of current that will stream under fault conditions. The PFC will continuously be the highest at the source of the installation as the impedance/resistance is always the lowest there. So as a regulation, if it’s not too extreme at the mains it will be fine everywhere else. This is because it will decrease due to the increase in resistance as we move further away from the origin. (ohms law I = V/R).
Because of the type of dissimilar supplies, you would assume to find a PSC value greater than a PFC value on both TT and TN-S systems, yet on a TNC-S system both the PFC and PSC readings should be same.
What is done During PFC and PSC Tests?
PSC is decided by the voltage and impedance of the supply system. It’s far of the order of some thousand amperes for a well-known domestic mains electrical set up, but can be as little as a few milliamperes in a separated extra-low voltage (SELV) device or as excessive as hundreds of heaps of amps in huge industrial strength systems
PFC is conducted at the source of the installation, like the main switch or at other switchgear connected straight to the tail from the electricity distributor’s metering device. Where a calculation is made at a point in the installation other than the source, such as a piece of switchgear served by a distribution circuit, it would not be the highest value for the installation.
Particular guardianship should be exercised during the testing summons, as flaw conditions are most severe at the origin of an installation, where this test is performed. The earthing conductor, main protective bonding conductors and circuit protective conductors should all be connected as for normal operation during these trials, because the presence of these and any other latitude ways to earth may reduce the impedance of the earth flaw loop and so increment the level of prospective fault current.
PSC will be greater than the PFC. Prospective fault current and short circuit current of a circuit is automatically calculated when making a loop impedance test. The calculation uses a nominal circuit voltage, not the actual circuit voltage.
Why PSC and PFC are Done?
Pfc and psc test is necessary for choosing the correct protective device for the circuit because it’s going to carry the maximum fault current flowing in a circuit. Regulation 612.11 of BS 7671 requires that the prospective fault current under both short circuit and earth fault conditions be determined for every relevant point of the installation.
How is PSC and PFC Performed?
The minor supply voltage used in the calculation is automatically chose depending on the real circuit voltage. The instrument uses the following voltage values:
Prospective Short Circuit Test Procedure
- PFC tester or the Prospective short circuit function of a multifunctional tester such as the Megger 1553 is chosen, and we make sure that the supply is ON, but the Main Switch is in OFF position.
- The test leads are joined on the incoming side of the Main Switch, one test lead on Line and another on the Neutral terminals of the Main Switch.
- TEST switch is pushed and a note of the value (kA) is made.
- For three phase installations each phase is tested separately and the measured reading (test between Line 1 and Neutral, then Line 2 and Neutral and last Line 3 and Neutral) is doubled.
- Some test meters need that the third (usually green) lead to be connected on the Neutral during this test. Please refer to the test meter manufacturer’s instruction.
Prospective Fault Current Test Procedure
- We use PFC tester or select the PFC function of a multifunctional tester such as the Megger 1553, and it has to be made sure that the supply is ON, but the Main Switch is in OFF position.
- Next, we connect the test leads on the Line and Neutral terminals of the Main Switch, as well as on the Earth terminal.
- The TEST switch is pushed and we make note of the reading (kA).
For three phase installations each phase is checked separately and the measured reading is doubled (L1 – N – CPC, L2 – N – CPC, L3 – N – CPC). - Having obtained these values by the measurements described above, we will select the highest value and write it down on the Electrical Installation Certificate as the value of PFC.
- The value of PFC obtained is compared with the breaking capacity of all the protective devices within the installation. The breaking capacity of the protective devices should be greater than the value of PFC.
Benefits of PSC and PFC Tests
- They give accurate results as its live testing
- The testing is simple and not much calculations are needed.
- Increased safety for employees and third parties
- Decreased Insurance Premiums
- Asset Data management and tracking systems.
- Small repairs of equipment made on-site to reduce down time
FACTORY ACCEPTANCE TESTING SERVICES
The Factory Acceptance Test (FAT) is a customized testing procedure that evaluates the equipment during and after the assembly process by verifying that it is built and operating in accordance with design specifications. FAT ensures that the components and controls are working properly according to the functionality of the equipment itself. As the name suggests, this testing is performed at the factory.
FAT must be conducted in a thorough and forthright manner. A poor or rushed FAT can lead to missed non conformities, which can only then be corrected after the equipment is installed—which in turn can wreak havoc on a project schedule.
Why use Factory Acceptance Testing Service From ETC
FATs are beneficial not just for the buyer and end users but for the manufacturer as well. Both parties can be assured that the equipment meets all the contractual specifications and any issues can be addressed before arriving at the customer’s site.
Our broad factory acceptance test is the most lucrative way to ensure that your equipment or plant operates correctly. As a highly qualified, independent third-party, we have the trusted skills and resources to perform steadfast testing. Alternatively, we can witness appropriate testing on your behalf. In many cases it is difficult to predict the correct operation of the safety instrumented system or consequences due to failures in some parts of the safety instrumented system. For that reason the FAT is a valuable check of the safety issues.
Factory acceptance test helps you to:
- Achieve independent proof of functionality, quality and integrity with our comprehensive checking process.
- Verify all important documents, such as manuals, instructions, plans, drawings, piping and instrumentation diagrams (P&IDs).
- Ensure that your equipment or plant performs as expected under the testable range of likely conditions, including mishandling and error.
What are the Process in Factory Acceptance Testing
The main objective of the FAT is to test the safety instrumented system (logic solver and associated software together). The tests are normally executed during the final part of the design and engineering phase before the final installation at the plant. The FAT is a customized procedure of checking the safety instrumented system and the safety instrumented functions according to the safety requirements specification.
Following are the points to remember while conducting Factory Acceptance Test:
- Provide a detailed test plan.
- Push the envelope, but use the right materials as well.
- Engage the operators and technicians
- Be smart about training.
- Create and follow a detailed “failure script.”
- Test parts replacement and changeover procedures
- Take your time.
- Get a good integrator.
- Work with your supplier, and your supplier will work with you.
- Know the difference between a Factory and Site Acceptance Test.
The purpose of the FAT is to verify the desired functionality of the machine. On acceptance of a FAT, you’ll be looking for items such as:
Completed Factory Acceptance Test Protocol
- Maintenance and users’ manuals
- Easy-to-use training materials (OPLs, videos, etc.)
- Standard work procedures
- Standard maintenance procedures
- Recommended spare parts lists
- Certificates of compliance
- As-built technical drawings (electrical, mechanical, pneumatic, and process schemes)
- Materials certificates and data sheets
- Main equipment data sheets
- Instruments calibration certificates
- Welding processes qualifications
How ETC Conduct Factory Acceptance Testing?
Before the FAT begins, the manufacturer should present the FAT procedure to the client for review and approval. The procedure should include testing of as much functionality as is practical in the factory and, where possible, should show pass/fail criteria or desired results for each item tested. Once the procedure is approved, the manufacturer should test the equipment before the FAT begins:
Step 1: Process done before Factory Acceptance Test (Pre-FAT)
A pre-planning is necessary for an efficient FAT. The procedures to carry out the FAT shall be well defined and documented in a proper way. Each test procedure shall be described in a logical sequence i.e. How to test the application software and hardware. The needed competence for involved test personnel is described during the planning. It is recommended that personnel with experience suitable for the intended process application and safety instrumented system deals with the FAT planning.
- The testing included in a FAT procedure should be largely derived from the performance criteria defined in the Functional Requirements Document(FRD), which is created by the project team early in the project planning process. The FRD should be the focal point for discussions when interviewing potential system integrators and should be included in the contract/purchase order package.These requirements should, therefore, be well known and understood well before time to develop the actual FAT protocol
- The system integrator/dealer should prepare and submit a FAT procedure well in advance of the FAT. This procedure should be reviewed and approved by the system owner/project manager. It should attempt to include testing of as much functionality as is practical in the factory, and check of all interfaces among equipment and systems. Where possible the procedure should show pass/fail criteria or desired results for each item.
- The dealer should also provide a schedule for the FAT showing all timing and sequence of testing.
- Prior to FAT all design approvals should be complete. This is to remove technical ambiguity from the FAT and prevent disputes over work that continues after FAT.
- The dealer should prepare a test facility that can be effectively used to conduct the FAT testing, including calibrated test equipment and any special test equipment.
- The dealer should compile a document set that can support the testing and serve as a reference for the test results, including:
- Contract specifications and copies of all references called out in the specification.
- All drawings for the project, including drawings received from other vendors that describe interfaces.
- Detailed testing check list, including pass/fail criteria.
- The dealer is to pretest the system before FAT. Failure to do this can result in wasted time during FAT, and potentially a prolonged extension of FAT while fixes are effected.
- If the system in question is large enough to impact the system owner’s facilities, laboratory layout or utilities or if there are any questions regarding moving the system into the owner’s facility, it is highly recommended that a person responsible for the owner’s physical plant/facility be invited to attend FAT.
Step 2: Process done During Factory Acceptance Test
- We review the specification line by line while checking the equipment or drawings for compliance with the specification, including any change orders.
- We inspect for workmanship
- Next we inspect for problems that can occur during installation or use of the equipment, for example, lifting points and safe access to components for maintenance, etc.
- We test of the equipment per the dealer’s approved procedure; these should include functionality testing and regulatory testing. Ad hoc testing may be required to define any major non-conformities revealed by testing.
- Next we note the software and firmware versions in the equipment being tested.
Step 3: Processes done After Factory Acceptance Testing
All the test cases of the FAT shall be explained in the documentation and furthermore if the objectives and criteria of the tests have been met or not. Exposed failures during the test are documented and the causes for the failures are also documented supported by essential actions to correct the failures. If there are modifications of the safety instrumented system it is necessary to carry out a safety analysis in order to determine if the safety is affected and if re-testing is necessary.
Benefits of Factory Acceptance Test
- Gain independent proof of functionality, quality and integrity with our comprehensive checking process.
- Verify all-important documents, such as manuals, instructions, plans, drawings, piping and instrumentation diagrams (P&IDs).
- Ensure that your equipment or plant performs as expected under the testable range of foreseeable conditions, including misuse and error.