The TWA series instruments are designed for six-winding resistance measurement of power and distribution transformers. As well as resistance measurement of inductive test objects. In addition, they provide powerful tap changer analysis options by using proprietary, non-intrusive DVtest features. They generate true DC ripple free current with automatically regulated measurement and discharging circuit.
The transformer measurements performed with the TWA instruments require only one single-step cable setup. Each transformer configuration has a special measurement algorithm. They are optimized for the fast stabilization of test results. The test current can be automatically passed through the HV and LV winding simultaneously in order to achieve shorter stabilization times.
The TWA40D model is a true three-phase instrument capable of simultaneously measuring winding resistances of three phases of YN configuration. As well as three-phase tap changer analysis. All TWA instrument models are capable of both single-phase and three-phase demagnetization. The DV-Win software, provides full control of all TWA functions from a PC and additional test and analysis modes and features, is included with the TWA instruments.
Resistance measurement of all tap positions in all
six windings performed in a single test
True three-phase on-load tap changer dynamic resistance measurement
Extremely quick measurement, single-step cable setup Automatic discharge process
Rapid automatic demagnetization
Built-in tap changer control unit
Temperature measurement channel
Winding Resistance Measurement
Test currents: 5 mA – 25 A DC (TWA25A)
5 mA – 40 A DC (TWA40D)
Output voltage: up to 55 V DC
Measurement range: 0,1 μΩ - 10 kΩ
Typical accuracy: ± (0,1 % rdg + 0,1 % F.S.)
Resolution
0,1 μΩ – 999,9 μΩ: 0,1 μΩ
1,000 mΩ – 9,999 mΩ: 1 μΩ
10,00 mΩ – 99,99 mΩ: 10 μΩ
100,0 mΩ – 999,9 mΩ: 0,1 mΩ
1,000 Ω – 9,999 Ω: 1 mΩ
10,00 Ω - 99,99 Ω: 10 mΩ
100,0 Ω – 999,9 Ω: 0,1 Ω
1 000 Ω – 9 999 Ω: 1 Ω
Data Storage
1000 internal memory positions
USB flash drive feature enables storage of
a huge number of measurements
AC Current Measurement Channel (TWA40D)
Resolution: 0,1 ms
Amplitude resolution: 16 bit
Current Clamp Meter Specifications
Nominal current: 300 ARMS or 450 A DCPK
Measuring ranges: 30/300 A
Frequency range: DC to 20 kHz (-3 dB)
Resolution: ± 50 / ± 100 mA
Accuracy: ± 1% of the reading
Environmental Conditions
Operating temperature:
-10 ºC - + 55 ºC / 14 ºF - +131 ºF
Storage & transportation:
-40 ºC - + 70ºC / -40 ºF - +158 ºF
Humidity 5 % - 95 % relative humidity,
non-condensing
Dimensions and Weight
Dimensions (W x H x D):
480 mm x 197 mm x 395 mm,18 9 in x 7 8 in x 15 6 in
Weight:12,8 kg / 28.3 lbs