Megger TPT420 LCD/LED Two-Pole Voltage Tester

Product Information

When the probes of a voltage tester are connected to two points in an electrical circuit (commonly one end to a suspected live conductor and the other to a ground source), a closed circuit or loop is formed. This allows electrical current to flow from the higher potential to the lower potential.

The EMU, in addition to an inductive voltage transformer, contains a tuning circuit and protection against ferroresonance (Figure 1). The tuning circuit is a reactor that compensates for magnitude errors and phase shift caused by the CVD, making it possible to have the CCVT with a characteristic on the secondary side that is similar, in terms of error and phase deviation, to that of a purely inductive voltage transformer. The instrument has abright, integrated LED torch to helpyou when working in poorly lit environments and, it is safetyrated at CAT IV 1000 V with an IP64 housing, and conforms to the latest IEC/EN 61243-3 and DIN VDE 0682-401 standards. For compliance, GS38 probe tip shrouds are provided as standard, along with a protective storage and carry pouch.

Megger VF5 Voltage Tester Technical Specifications 

And it’s the same with a surge test generated by a Baker DX tester. It applies a voltage and rise-time to enable you to see the inter-coil response, but with a signal controlled in voltage, time and energy, so that the impact on the motor is similar to the spikes that the motor receives as a result of typical power-system variations during everyday operation. Power frequency (50 / 60 Hz) power factor / tan delta testing has been the standard for evaluating the condition of solid and liquid insulation in transformers for over 100 years.With the introduction of 1 Hz power factor / tan delta testing, Megger is revolutionizing insulation diagnostics. When testing at 1 Hz, the dielectric losses due to moisture, contamination and increase liquid conductivity are better observed. Power factor or tan delta test at 1 Hz provides superior detection sensitivity to early and advanced insulation deterioration. Combined with power frequency measurement, 1 Hz delivers immediate insulation assessment without the need for trending or proprietary databases.

In addition to the unit's adaptable auto-ranging voltage and continuity tests, the Megger MET1000 has a built-in current clamp for AC current measurement to 200 A. With true RMS AC measurements, a phase rotation test, and single pole voltage test built in, the MET1000 is a truly multi-purposeelectrical test instrument, ideal for use in commercial, industrial, and domestic environments. It even comes with GS38 shrouds, provided as standard, to ensure compliance with the latest standards. A basic ratio test can be carried out by exciting the primary side of the CCVT with a 10 kV source and measuring the secondary voltage with a digital multimeter. However, this supplies no measurement of phase deviation, which is required to validate the accuracy of the CCVT. Continuity function: detects continuity between 0 and 500kΩ and alerts the user by issuing an audible and visual alert

What’s Included?

CCVT construction varies between manufacturers, models and year of fabrication. Knowledge of the construction is critical when deciding what and how to test. As mentioned previously, some CCVTs are equipped with a potential grounding switch located below C1, at the intermediate voltage terminal (IVT), and a carrier grounding switch below C2 at the low voltage terminal (LVT), as shown in Figure 3. In some CCVTs, however - mainly modern types - the low voltage terminal may not accessible. Understanding the construction characteristics and location of the IVT and LVT is therefore important when determining appropriate connections for testing and deciding whether the ground switches need to be open or closed for the required measurements to be made. On older style CCVTs, the potential terminal is typically accessible. However, for modern CCVTs such as those supplied by Trench, the potential terminal is inaccessible. Even in these cases, however, C2 can still be tested. CCVTs have a potential ground switch that provides the means to ground the potential terminal. With the potential ground switch closed, the carrier terminal can be energised, a low voltage lead connected to the line terminal (top of C1), and a C2 test performed in the GST-guard mode. Note that the carrier terminal must be disconnected and isolated from ground potential and the drain coil (also, if applicable, from any accessory leads) for the C2 test. In addition, the test voltage (typically 500 V) used to energise the carrier terminal must not exceed the voltage rating of the terminal. In summary: A bad turn will short and this will be shown by a jump in the ringing frequency of the coil (it becomes in effect a ‘different’ coil at this point in the test). Large frequency jumps can be clearly seen on the tester display, but the instrument’s software also uses mathematical analysis to reveal anomalies that are less easy to spot by eye.