For additional clia cytology pt information, refer to the links below. Practical exams are given only at approved accredited testing facilities. This full featured product combines all of the metering ct test. The normal range of the current transformer for measuring the current is 5a or 1a whereas the standard voltage at the secondary winding of the potential transformer is up to 110v. Insulation tests on current transformers rated 600v or less are usually performed at vdc. A current transformer ct is an instrument transformer in which the secondary current is substantially proportional to primary current and differs in phase from it by ideally zero degree ct accuracy class or current transformer class.
When cts and pts are used in a metering installation, the installation is known as being transformerrated. Reexaminations for this endorsement shall be in accordance with the reexamination requirements of aws qc1. The requirements for revenue metering applications are not included in this swp. Pt candidates shall pass with a minimum of 70% correct answers per exam part and an 80% composite average of all parts the pt written examinations. In its application to a current transformer, it is the number representing the amount by which the primary load current may be increased over its nameplate rating without exceeding the allowable temperature rise. The cms approved cytology proficiency testing pt programs for calendar year 2019 are. A current transformer is similar to a electrical power transformer to some extent, but there are some difference in construction and operation principle. Ct ratio with burden testing secondary connection is made through the test switch same connection that is used for the rest of the site testing. Ct analyzer current transformer testing, calibration and. Instrument transformer basic technical information and. Ensure the ct is connected to system properly in all respect primary and secondary.
This instrument measures ct admittance, ct ratio, ct primarytosecondary phase angle. Ct is essentially tested as a voltage transformer by applying voltage to the ct. Test results are accepted by police and public service agencies throughout connecticut and beyond. These conventional testing methods include measuring a number of parameters, such as the short circuit impedance, transformers ratio, magnetizing current, winding resistance and dynamic winding resistance of the tap changer. The primary current of minimum of 25% rated primary current to be injected on primary side of ct with secondaries shorted and the secondary current can be measured and recorded for all cores limits. Adopt lcd, selfequipped mini type printer supporting field printing. From a maintenance and testing program to a maintenance program which includes at least one of the following activities. Current transformer testing on site presentation calmet. Pricing is based on a persample basis and payment is due at the time of order. T2000 test set for testing cts, pts, primary injections. The transformation ratio of the current transformer is always remained high, whereas for the potential transformer its remains low.
To confirm the physical condition and electrical characteristics of current transformer installed in the installation. The importance of current transformer tests is often underestimated. Turns ratio tests optional test this test is to ensure the turns ratio of ct at all taps. It uses a combination of xrays and a computer to create pictures of your organs, bones, and other tissues. Voltage transformer testing swp page 3 of 19 standard work practice sp0508 ver 7 ergon energy corporation limited abn 50 087 646 062 if any risks cannot be managed or reduced to an acceptable level, do not proceed with the task and seek assistance from your supervisor. Abstractcurrent transformer ct saturation, while a fairly common occurrence in protection systems, is not often clearly. This article is a basic guideline for pt testing using the most basic of equipment and is arranged in accordance with the neta standards for easy reference. Excitation characteristics test transformation ratio test polarity power frequency withstand test. Trouble shooting of all electrical circuits, control and protection circuits coordination with client in as built scheme drawing submission, test report submission. Ct analyzer the number one in current transformer testing. Every pt test form should include the serial number, model number, ratios and accuracy.
A practical guide to ct saturation ariana hargrave, michael j. Potential transformer testing ptvt i cowrote an article for the neta world magazine in 20042005 that covers several different manual techniques for potential transformer testing that explains several lowtech solutions for potential transformer testing. A test set operator connects the leads, pushes the buttons, and records the. If youre experiencing symptoms, contact your medical provider. The following values can be determined using the ctpt analyzer. Testing of ct, pt, cvt, circuit breaker, switch gear and power transformer operation and maintenance of power plant and substation. This protects connected metering devices from overloading in the presence of fault level current flows.
Burden artificial load for voltage and current transformers electronically compensated current and potential burden according iec 60044 and ansiieee c57. Metering class ct burdens are displayed as secondary ohms. All work to be done with voltage transformer deenergised. Some people refer to the meters that use a ct pt combination or just cts as a current transformer meter.
Back to the basics current transformer ct testing as test equipment becomes more sophisticated with better features and accuracy, we risk turning our field personnel into test set operators instead of skilled field service technicians. Ratio testing with applied burden is the most accurate and complete approach for testing at ct in service. Remove the neutral ground and isolate the ct from any associated burden. Primary injection testing is essential in commissioning and verifying a protection scheme since the secondary injection test does not check all the components in the system and the condition of the overall protection installation. The mrct can be controlled via meggers smart touch view interface stvi controller, a full color, high resolution, lcd touch screen which allows the user to perform manual and automatic testing quickly and easily using the manual test screen, as well as using preconstructed test routines. With our testing system, you can use a single device to determine all of these parameters in an easy way. Ct rated meters are also typically demand meters as well. Such specially constructed transformers with accurate turns ratio are called as instrument transformers. Efficient current transformer testing with omicron ct analyzer. Rating factor rf is a term, which applies to a current transformer. Testing and protection of current transformer practical experiences.
Testing potential transformers relay testing training. Transformers has been made far simpler with the model 590jv2. A computed tomography ct or cat scan allows doctors to see inside your body. The ratio determines the ct operating characteristics and is used as reference for. Of this 60%, it is possible to pick up 97% of cases using chest ct alone. Use results from a single test to apply for multiple positions with no additional cost.
Cytology pt enrollment table pdf national cytology pt results since 2005 pdf. Some people refer to the meters that use a ct pt combination or just ct s as a current transformer meter. Potential transformer testing ptvt valence electrical. Gf106 ctpt tester is mainly used for field testing, it can finish the measurements m and protection p class ct, pt and typ class ct. Ct pt testing equipment on sales quality ct pt testing. Back to the basics current transformer ct testing valence. The ct ratio is the most important piece of information regarding the ct and must be recorded from the nameplate or the design criteria. Aafppt can provide samples for offschedule or reinstatement testing based on sample availability. Below features make gw ctpt analyzer and ideal tool for ctpt manufacturer, testing labs, substations upto 765kv, power plants etc. You can transform the voltage or current down with a transformer whose turns ratio is accurately known, then measuring the stepped down magnitude with a normal range instrument. The testing facilities at xihari also include an extension environmental laboratory. This new ctpt testing set are based on low frequency and variable frequency methods which lead to the great reduction in weight and high knee point test range.
The circuit connection shall be made as shown figure 4. The following table lists the tests that can be performed on ct and vt. Transformerrated services run in parallel with the service. Cts for metering purposes must have a high degree of accuracy to ensure. Common electrical tests on power transformers omicron.
The original magnitude can be determined by just multiplying the result with the transformation ratio. Acute diarrhea lipid screening anemia pap smear referral ana pointofcare testing. About 60% tested positive with the rtpcr, but 88% with chest ct scan. Prior to testing, short the primary winding of the ct under test by connecting h1 and h2, then short the secondary winding of the ct under test by connecting x1 and x2x5.
Compare equipment nameplate data with drawings and specifications. Markings on current transformers ct and potential transformers pt have been occasionally misapplied from the factory. Gw ctpt analyzer is an all in one solution for testing all type of ctpt as per iec standards. When the circuit burden gets too large, the ct secondary voltage becomes distorted. The model 505 transformer analyzer is designed for testing current transformers ct and potential transformers pt without interruption of the customers service. These services are for general questions about covid19. A routine series of diagnostics and testing for your current transformer should include ct saturation testing to identify the knee point against ieee or iec standards, ct ratio tests to identify that the voltage ratio is within expected parameters and current transformer resistance testing for both the transformer windings and ct insulation. Cv engineer electrical testing and commissioning ht, lt. Thompson, and brad heilman, schweitzer engineering laboratories, inc. Instrument transformers potential transformer, current transformers for high voltage and current measurement. It is an equipment with high roi return on investment. Ct pt testing manufacturers in india udeyraj electrical. Performing field test measurements of current and potential.
1370 128 10 399 1495 952 271 189 61 271 1221 895 317 1282 841 737 1261 1483 1387 317 484 1420 1219 53 619 749 571 1085