Xi'an Xu&Hui Electromechanical Technology Co., Ltd.
| Test Object | On-Load Tap Changer of Power Transformer |
| Operating Temperature | -10C to 50C |
| Transition Resistance Range | 0.3-100 Ohm in Three Gears |
| Time Accuracy | +/-(0.1% Reading +/-0.2ms) |
| Working Power | AC220V +/-10%, 50Hz |
| Open-Circuit Voltage | 24V |
| Test Modes | With Winding, Without Winding |
| Interfaces | RS232, USB, Printer |
| Payment Terms | T/T |
| Supply Ability | 3000unit/year |
| Delivery Time | 5-8 work days |
| Packaging Details | wooden packaging |
| Sampling Rate | 20kHz |
| Transition Time Range | 0-320ms |
| Data Storage | 500 Groups Built-In |
| Resistance Accuracy | +/-(5% Reading +/-0.1 Ohm) |
| Winding Types | YN, Y, Delta |
| Measured Items | Transition Waveform, Time, Resistance, Simultaneity |
| Display | 7-inch High-Brightness LCD |
| Output Current | 1.0A, 0.5A, 0.2A |
| Brand Name | XZH TEST |
| Model Number | XHYZ1668 |
| Certification | ISO CE |
| Place of Origin | Xi'an Shaanxi China |
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Product Specification
| Test Object | On-Load Tap Changer of Power Transformer | Operating Temperature | -10C to 50C |
| Transition Resistance Range | 0.3-100 Ohm in Three Gears | Time Accuracy | +/-(0.1% Reading +/-0.2ms) |
| Working Power | AC220V +/-10%, 50Hz | Open-Circuit Voltage | 24V |
| Test Modes | With Winding, Without Winding | Interfaces | RS232, USB, Printer |
| Payment Terms | T/T | Supply Ability | 3000unit/year |
| Delivery Time | 5-8 work days | Packaging Details | wooden packaging |
| Sampling Rate | 20kHz | Transition Time Range | 0-320ms |
| Data Storage | 500 Groups Built-In | Resistance Accuracy | +/-(5% Reading +/-0.1 Ohm) |
| Winding Types | YN, Y, Delta | Measured Items | Transition Waveform, Time, Resistance, Simultaneity |
| Display | 7-inch High-Brightness LCD | Output Current | 1.0A, 0.5A, 0.2A |
| Brand Name | XZH TEST | Model Number | XHYZ1668 |
| Certification | ISO CE | Place of Origin | Xi'an Shaanxi China |
| High Light | Reads YN Y Delta Directly ，Transition Resistance 0.3 to 100 Ohm ，500 Data Groups Built-In Storage | ||
The XHYZ1668 is an on-load tap changer (OLTC) waveform and transition resistance tester for power transformers. The on-load tap changer is the only moving part connected to the transformer circuit, and its inspection has drawn increasing attention: handover and preventive test regulations require the tap changer's action sequence to be checked and its switching time to be measured. This instrument measures the transition waveform, the transition time, the instantaneous transition resistance values and the three-phase simultaneity of the on-load tap changer, and displays the resistance value directly for YN, Y and Delta transformers without any conversion.
With a high degree of intelligence and a full Chinese menu, the instrument is simple to operate, small, light, and strongly immune to interference, greatly reducing the workload of field staff. It is an ideal instrument for power generation and supply units and for the transformer manufacturing industry to ensure safe production and improve product quality.
Who It Is Built ForThis is not a general cable instrument; it is a transformer test set for the specialists who own the tap changer's performance data:
Transformer manufacturers' factory and type-test engineers who must verify, on every unit leaving the line, that the on-load tap changer switches in the correct sequence with the right transition waveform, transition time and transition resistance, and that the three phases act together. The direct-reading display for YN, Y and Delta windings removes the manual conversion that slows a production test bench down, and the internal storage of 500 data groups keeps a full batch of records on the instrument.
Power generation and supply units' commissioning and preventive-test crews who carry out handover and preventive tests at substations, often on tap changers that have stood idle for a long time. These teams rely on the waveform to judge the health of the change-over switch: an aging energy-storage spring, a broken transition resistance, or a broken strand in a lead can all be read from the transition waveform before it becomes a failure.
| Method | Connection | Note |
|---|---|---|
| With Winding | Remove the leads on the three sides of the transformer under test and short-circuit and ground the non-test side (usually the medium-voltage and low-voltage sides) three-phase. Clamp the yellow, green, red and black test clips to phases A, B, C and the neutral of the regulating side (usually the high-voltage side), and connect the other ends to the instrument terminals A, B, C and N. | The action time is about 3-7 ms longer than the without-winding test. |
| Without Winding | Clamp the yellow, green and red clips to X1(A1), Y1(B1), Z1(C1) of the tap changer and short them to X2(A2), Y2(B2), Z2(C2); connect the black clip to the neutral. The A, B, C moving contacts are shorted together and connected to the instrument neutral terminal. | Other steps are the same as the with-winding test. |
| Y-type, Neutral Not Brought Out | With the neutral inaccessible without removing the core, test two phases at a time, for example A and B, treating C as the neutral. The screen shows only two sets of waveforms and data. | Transition resistance conversion: measured R' gives actual R = 1/3 R' for a two-phase test and R = 1/2 R' for a single-phase test. |
| Delta-type Winding | Wiring is the same as for the other transformers; operation and data analysis are unchanged. | Transition resistance conversion: R = R' for a two-phase test and R = 2/3 R' for a single-phase test. |
Output current selection: choose the current gear by the transition resistance value — 1.0A for 1-20 Ohm, 0.5A for 5-40 Ohm and 0.2A for 20-100 Ohm. After the current is selected, a preset trigger resistance is set automatically and normally does not need to be changed: increase it to lower the trigger sensitivity when false triggering occurs, or decrease it to raise the sensitivity when triggering fails.
To protect the equipment, the output current of each measurement lasts 2 minutes; beyond two minutes the output stops automatically and the instrument returns to the parameter setting screen, so the tap changer must be operated to switch within two minutes of starting the measurement.
Typical Fault Waveforms and What They MeanThe transition waveform is the fastest way to judge a tap changer's condition. The reference parameters are: R0 — coil resistance and test lead resistance; R1 / R2 — transition resistance 1 and 2; T0 — three-phase simultaneity, based on the earliest phase detected switching; T1 / T3 — operating time of transition resistance 1 and 2; T2 — bridging time; T4 — transition time.
| Waveform Symptom | What It Indicates |
|---|---|
| The time before bridging is too long, reaching 50 ms (three times the normal time), on not just one phase but nearly all three | A typical case of an aging fast-mechanism energy-storage spring, causing the speed to slow down. |
| Phase A shows symmetrical zero-crossing segments between single-to-double (3-4) and double-to-single (4-3) on the odd side, and the transition resistance reads far above 50 Ohm (over 50 Ohm can be regarded as open circuit) | A typical transition resistance defect; inspection after lifting the core found the odd-side transition resistance was broken. |
| The waveform oscillates because the sensitivity was set too high and the test was run in the 3-2 direction (increasing inductance) | Reduce the sensitivity appropriately; testing in the 1-n direction then gives normal results. |
| The phase A waveform is messy and the transition resistance reads only 0.3-0.5 Ohm, the same for positions 1-7 | Inspection found the phase A change-over switch lead had a broken strand in its flexible connection, shorting the phase A transition resistance (without fully disconnecting it); the waveform was normal after field repair. |
The instrument judges the waveform automatically by default; the manual processing mode is intended only for printing when the automatic result is incorrect, and is not recommended in normal use.
Technical Specifications| Output Current | 1.0A, 0.5A, 0.2A |
| Transition Resistance Range | 0.3-20 Ohm (1.0A); 5-40 Ohm (0.5A); 20-100 Ohm (0.2A) |
| Transition Time Range | 0 - 320 ms |
| Open-Circuit Voltage | 24V |
| Transition Resistance Accuracy | ±(5% of reading ± 0.1 Ohm) |
| Transition Time Accuracy | ±(0.1% of reading ± 0.2 ms) |
| Sampling Rate | 20 kHz |
| Data Storage | Built-in storage, up to 500 groups |
| Display | 7-inch high-brightness LCD |
| Interfaces | RS232 serial port, USB port, high-speed printer |
| Ambient Temperature | -10℃ to 50℃ |
| Ambient Humidity | ≤ 85% RH |
| Working Power | AC 220V ±10%, 50 ±1 Hz |
| Item | Unit | Qty | Item | Unit | Qty |
|---|---|---|---|---|---|
| Host | set | 1 | Test line | set | 1 |
| Power cable | pc | 1 | Fuse | pc | 2 |
| Printing paper | roll | 1 | Ground wire | pc | 1 |
| Cable bag | pc | 1 |
Contact XZH TEST for configuration advice and a quotation on the XHYZ1668T on-load tap changer waveform and transition resistance tester.
Company Details
Business Type:
Manufacturer
Year Established:
2013
Total Annual:
1000000-5000000
Employee Number:
50~100
Ecer Certification：
Verified Supplier
Xi'an Xu&Hui Electromechanical Technology Co., Ltd. /Xian XZH Electric Power Technology Co., Ltd. Has found in 2013, located in Xi'an, China. which is a highly experienced team dedicated to developing electrical... Xi'an Xu&Hui Electromechanical Technology Co., Ltd. /Xian XZH Electric Power Technology Co., Ltd. Has found in 2013, located in Xi'an, China. which is a highly experienced team dedicated to developing electrical...
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