Current transformers are often used to convert high currents to a lower one which is safe enough for measuring instruments or protective devices to use. It is also used in monitoring the power facility during operation. It is important to keep them in good working condition because this can cause inaccurate measurements or sometimes damage the electrical facility.READ MORE >>
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A three phase transformer winding resistance meter, the Vanguard TRM-403 Transformer Resistance Meter can accurately measure resistance from 1 micro-ohm to 500 Ohms, it can be used as a micro-ohm meter to measure EHV circuit breaker contact resistance, or for any low resistance measuring application.
The Vanguard TRM-403 Transformer Resistance Meter can perform a special test to collect data automatically for up to 90 minutes (at 60-second sampling intervals) or 45 minutes (at 30 second sampling intervals). The test data is recorded with a time stamp. All test results can be printed on the unit’s built-in 2.5” wide thermal printer.READ MORE >>
For measuring winding resistance of highly inductive power transformers consider the Vanguard LTCA-40 Load Tap Changer Analyzer.
Triple resistance-reading channels allow the Vanguard LTCA-40 Load Tap Changer Analyzer to measure three winding resistances simultaneously. Four-wire (Kelvin) connections provide high accuracy and require no lead compensation. A special feature of the Vanguard LTCA-40 is its ability to measure and graph the resistance trace of a transformer LTC during operation. Using a 60Vdc power supply, the Vanguard LTCA-40 is capable of outputting 40 amperes.READ MORE >>
Current transformers (CTs) serve as a critical and essential interface in the world of electrical power. At first glance, the role of a CT may appear to be simple however, CTs function as one of the most important components of the electrical system infrastructure. The performance of these devices is reflected in the correct operation of metering devices, relays, and circuit breakers. Therefore, a comprehensive yet simple approach to evaluating the condition of low-, medium-, and high-voltage CTs is paramount for testing service companies and utility operators.READ MORE >>
An electronic device that measures electrical resistance, ohmmeters come with different levels of sensitivity; some are designed to measure low-resistance materials, while others measure higher resistance.
An ohmmeter functions by passing a constant current or voltage though an object, such as voltage from a battery, and then measuring the resulting current with an ammeter after it passes through the resistance. The higher resistance the material has, the less current will pass through it. An ohmmeter is typically not used to measure resistance across an entire circuit, but rather through different parts of the circuit, although it can be used to test that a circuit is not broken. Components of a circuit can be removed and tested individually for resistance.
The Vanguard EZCT-2000A Automated CT Test Set is a microprocessor-based Current Transformer Test Set capable of performing Current Transformer (CT) excitation test, measure the CT current-ratio and polarity and CT winding resistance automatically.
The CT excitation test is performed using the ANSI/IEEE C57.13.1, IEC 60044-1 test method. The test voltage range for the CT excitation test (50 Vac, 300 Vac, 500 Vac, 1200 Vac or 2000 Vac) can be selected, and then the test voltage is raised and lowered automatically by the Vanguard EZCT-2000A Automated CT Test Set.. The excitation test voltage and current data is collected and stored in the unit’s internal memory. Any of the 10 possible combinations of X1 to X5 can be tested since all of the unit’s test leads can be connected to all of the CT output terminals at the same time. Up to 10 excitation tests can be stored in one record. Once the test is completed, test results can be printed and excitation curves can be plotted on the built-in 4.5-inch wide thermal printer.READ MORE >>
The Vanguard TRM-403 Transformer Resistance Meter can provide a fast and stable reading of very large transformers by utilizing a 60Vdc power supply.
The Vanguard TRM-403 ‘s test current is selectable from 1A to 40A, can accurately measure resistance from 1 micro-ohm to 500 Ohms, and can be used as a yes
micro-ohm meter to measure EHV circuit breaker contact resistance, or for any low resistance measuring application.READ MORE >>
The Vanguard Auto-Ohm 100 Ampere Micro-Ohmmeter applies a true DC current from 10A to 100A to the resistance load to be tested. Any test current setting can be selected by using the function control knob on the front panel.
The Vanguard Auto-Ohm 100 Ampere Micro-Ohmmeter controls the test current’s rise and fall rates by using a switching DC power supply and a current regulator circuit.READ MORE >>
The Vanguard TRI-PHASE True Three Phase TTR can be used as a stand-alone unit or can be computer-controlled. It can be operated locally using its alpha-numeric keypad and rotary switch. Information is displayed on a back-lit LCD screen (128 x 64 pixels) that is viewable in both bright sunlight and low-light levels.
The Vanguard TRI-PHASE True Three Phase TTR can store up to 112 test records and 128 test plans in Flash EEPROM. Test records or test plans can be stored or transferred to and from a PC via the available interfaces (RS-232C port, USB port, USB Flash drive port).READ MORE >>
The gaps in joined conductors may accumulate contaminants like moisture, dirt and grease, and as the contaminants accumulate between the joined metals, they introduce resistance. Used to measure junction resistance of joined conductors, Micro-Ohmmeters can evaluate the internal condition of the joined metals.READ MORE >>
The Vanguard LTCA-40 Load Tap Changer Analyzer is designed to accurately measure the winding resistance of highly inductive power transformers. The unit’s triple resistance reading input channels can measure three winding resistances simultaneously.
A special feature of this device is its ability to measure and graph the resistance trace of a transformer LTC or voltage regulator contact during operation. One resistance input channel is dedicated to this feature. The Vanguard LTCA-40 Load Tap Changer Analyzer provides stable resistance readings of very large transformers by utilizing a 60 Vdc power supply capable of outputting a test current up to 40 Amperes.READ MORE >>
Vanguard’s EZCT Automatic CT test sets accurately measure what is going on inside transformers. Their durable automated system can test turns ratio, winding polarity and excitation current without the need for bushing or current transformer removal all using a microprocessor based process. The EZCTs allow simplified testing in the field with results printed using the onboard thermal printer or stored for later retrieval using a PC or laptop.READ MORE >>