OEM dielectric loss capacitance tester Factory - Bulk Supply and Specification Guide
How It Is Built and What That Changes
The build method decides the measurement floor more than any datasheet claim. Each unit starts with a precision-wound high-voltage transformer, vacuum-impregnated to eliminate partial-discharge sites that would otherwise raise the loss tangent reading by 10-4 or more.
Automated winding tension control keeps inter-layer capacitance repeatable within ±0.5 pF across a production lot. That repeatability is what lets a buyer quote a single calibration certificate for a batch of fifty instruments instead of individual reports.
Process capability note: the same winding cell produces 12 kV and 20 kV models by changing the fixture set. Tooling amortisation drops 18% when the order exceeds 30 units of a single voltage class.
After impregnation, the assembly moves to a shielded PCB station where the bridge circuit and digital integrator are mounted on a four-layer board with controlled impedance traces. The board undergoes a 24-hour burn-in at 50 °C while the firmware runs a self-calibration loop against an internal reference capacitor.
Measured Performance in Real Use
Consistency is set at the forming stage. In field service, a utility crew testing 220 kV transformer bushings sees a typical dissipation factor spread of 0.0003 to 0.0015. The instrument must resolve 0.00005 at 10 kV without drifting more than 0.00002 over an eight-hour shift.
Measurement Range
0.1 pF – 2000 pF (capacitance)
0.00001 – 1.0 (tan δ)
Accuracy
±(0.5% reading + 0.00002) at 23 °C ±5 °C
Test Voltage
0.5 – 20 kV RMS, adjustable in 100 V steps
Frequency
15 Hz – 400 Hz, synthesiser-locked
Weight
12 kg (bench), 8 kg (portable)
Dimensions
420 × 310 × 180 mm (bench)
350 × 260 × 150 mm (portable)
| Inspection Point | Method | Acceptance Criteria |
|---|---|---|
| High-voltage transformer partial discharge | IEC 60270 compliant detector, 20 kV pre-stress | < 5 pC at 1.2 × rated voltage |
| Bridge balance drift | Automated 100-cycle sweep at 50 Hz | Δtan δ < 0.00001 over 1 hour |
| Temperature coefficient | Chamber soak -10 °C to +50 °C, 2 h dwell | < 0.000005/°C on 100 pF reference |
| EMI susceptibility | IEC 61000-4-3, 10 V/m, 80 MHz – 1 GHz | Reading deviation < 0.00003 |
Matching the Product to the Buyer's Need
Process choice shows up later as total cost of ownership. A laboratory that runs 200 tests per year on 400 kV GIS compartments benefits from the bench model's continuous-duty transformer and built-in reference capacitor. A field crew that moves between substations twice a week needs the portable version with its ruggedised handle and battery option.
Bench Configuration
Fixed 19-inch rack ears, forced-air cooling, dual-channel bridge for simultaneous C and tan δ, optional IEEE 488.2 interface.
Portable Configuration
Integrated Li-ion pack (8 h typical), IP54 enclosure, single-channel bridge, USB-C for data logging, shoulder strap included.
| Construction Element | Bench Grade | Portable Grade |
|---|---|---|
| Transformer core | Grain-oriented silicon steel, 0.23 mm lamination | Amorphous alloy, 0.025 mm ribbon |
| Enclosure | Powder-coated 1.5 mm steel | Glass-fibre reinforced polycarbonate, 3 mm wall |
| Calibration reference | Internal 100 pF ±0.01%, temperature compensated | External 100 pF standard (supplied separately) |
| Typical lead time (units) | 6 weeks for 1–10, 10 weeks for 50+ | 4 weeks for 1–10, 8 weeks for 50+ |
Buying Mistakes That Lead to Returns
The most frequent return reason is a voltage-class mismatch. A buyer specifies 12 kV for 132 kV cable testing, then discovers the test voltage must exceed 1.5 × operating voltage for meaningful tan δ data. The 20 kV model is required, and the price delta is 22%.
- Ordering the portable unit without the battery pack, then facing 4-week retrofit lead time.
- Skipping the communication interface spec; the lab's automation software only speaks SCPI over GPIB.
- Assuming the internal reference capacitor covers the full 2000 pF range — it only validates up to 500 pF.
- Neglecting to request the high-voltage cable set rated for the chosen test voltage; standard leads are 10 kV max.
A second wave of returns comes from calibration drift after the first year. The factory calibration interval is 12 months, but environments with >70% RH and daily temperature swings >15 °C can halve that interval. Buyers who budget for annual recalibration at the factory avoid the 30% surcharge for expedited turnaround.
Ordering, Tooling and Lead-Time Questions
What is the minimum order quantity for custom voltage ranges?
Five units. Below that, the fixture changeover cost is absorbed into the unit price, adding roughly 15% per instrument.
How does tooling amortisation affect unit cost at different volumes?
The winding fixture set costs $4,800. At 10 units it adds $480 each; at 50 units it adds $96 each. The same fixture serves both 12 kV and 20 kV models if the order mixes voltage classes.
Can we supply our own branding and front-panel overlay?
Yes. Provide vector artwork (AI or EPS) at least 300 dpi. The overlay uses UV-cured polycarbonate with adhesive rated for -20 °C to +70 °C. Tooling for a custom overlay is $1,200 and adds two weeks to lead time.
What calibration documentation ships with each unit?
A factory calibration certificate traceable to national standards, listing measured values at 0.5, 1, 5, 10, and 20 kV with uncertainty budgets. ISO 17025 accredited calibration is available as a $350 per unit add-on.
How are instruments packaged for export?
Each unit sits in a custom-cut polyethylene foam insert inside a double-wall corrugated carton (ECT 48). Bench models include a palletised crate for quantities over five. Humidity indicator cards and desiccant sachets are standard.
Ready to review specifications for your next order?
Request a Specification Review
