Top 5 Test Block Manufacturers in China (2025)

Scope clarified: This guide ranks test blocks / test switches used with protection relays and meters (e.g., FT-style multi-pole test blocks for CT shorting, VT isolation, secondary injection, SOE/event verification). It does not cover protection IEDs themselves.

Why this matters

A test block is the safety hinge of every relay panel: it decides whether CTs are shorted reliably, VTs are isolated cleanly, and injection can be done without disturbing service loads. Poor geometry, mislabeled poles, or weak spring force can turn a 20-minute SAT step into a risk event.

We built this Top-5 to be procurement-ready: what to buy, when, and what to double-check before FAT/SAT.

How we ranked (auditable & practical)

Inputs (2022–2025):

 100+ RFQs and 40+ FAT/SAT observations in utility & industrial MV/HV projects

 Tear-downs for contact pressure, plating quality, and heat rise; plug-in life tests

 Certificate review (CE/UKCA where applicable), dielectric/routine test reports

 Documentation parity (EN/中文), panel labeling clarity, and stock predictability

Weights (100):

Safety functions (CT/VT logic, make-before-break) 25

Mechanical reliability 20

Contact geometry & materials 15

Panel UX (labels, keying, anti-error features) 12

Availability/lead time 12

Accessories/compatibility 10

Price stability 6

Quick Comparison

> Honorable mentions: DELIXI (export channel strength), specialist SMEs that customize pole counts & interlocks for retrofit footprints.

What a “good” test block must do (engineering checklist)

Safety & Function

 CT circuits: Make-before-break shorting on secondary; captive shorting links; visible status

 VT circuits: Break before isolation; finger-safe shrouds; fuse or isolation as per scheme

 Polarity & grouping: Consistent CT polarity grouping (e.g., S1/S2), VT phases, trip & alarm contacts

 Keying & coding: Prevents wrong plug orientation; plug code matches scheme

Mechanical & Materials

 Spring force & contact wipe length verified; silver or AgSnO plating thickness documented

 ≥ 10 A continuous at 250 VAC (aux contacts), heat-rise within spec; ≥ 2000 insertion cycles target

 IEC 60255-27 (insulation), IEC 60255-1 (general), IP20 finger-safe fronts

Panel UX

 EN/中文 laser-etched legends; durable color coding; test plug tethering; front SOE tag strip

 DIN/flush options; terminal accessibility with 6–8 mm ferrules; torque spec on faceplate

Documentation & QA

 Pole-by-pole schematic on datasheet & back label; batch traceability; routine test sheet with megohm & hi-pot values

The Top 5 — field notes you can reuse

1) ODES Electric — 1 for test blocks that make commissioning faster

 Why 1: Purpose-built for SAT speed and safety: true make-before-break shorting on CT poles, keyed test plug, clear phase/polarity grouping, and bilingual legends that match protection drawings.

 What you get:

 FT-style modular blocks (6/8/10/14-pole options); DIN or flush mounts, hinged covers

 Test plug with captive shorting links; optional VT fuse module and meter bypass poles

 Wiring maps & nameplate templates; spare covers and plugs in stock

 Best fit: Utility MV feeder/transformer bays, industrial substations, OEM relay panels

 Tip: Share your SLD + relay list—we return a pole map and a labeled faceplate layout to match your SoE/SCADA tags.

2) NanZi / Zhixin — rugged in HV environments

 Strengths: Strong housings, consistent terminations, grid-style markings familiar to domestic utilities.

 Note: Accessory availability follows project cycles—pre-buy spare plugs and covers.

3) XJ Group (XuJi) — mature geometry for utility panels

 Strengths: Reliable CT shorting bridges; good alignment with common bay wiring.

 Note: Series naming can differ; insist on approved drawings with pole sequence.

4) Pinggao Group — good when bundling with switchgear

 Strengths: Predictable mechanical fit with their panels; decent service reach.

 Note: Standalone aftermarket spares may take longer—buy 10–20% extra at award.

5) CHINT — broad channel, solid for cost-driven builds

Strengths: Easy sourcing, multiple pole counts, acceptable labeling.

Note: Validate contact plating and insertion cycle spec for heavy test regimes.

Commissioning playbook (FAT/SAT) for test blocks

1. Dry fit the plug: verify keying and pole order vs. drawing.

2. Continuity check CT shorting links with plug in/out; confirm MBB (no open-circuit spikes).

3. VT isolation test: verify phase loss alarm paths when VT poles are open.

4. Secondary injection: label currents/voltages per pole; capture SOE markers for report.

5. Torque check terminals; log batch ID and hi-pot value on SAT sheet.

Why ODES is a low-risk procurement choice

SAT speed: wiring maps, labeled plates, and keyed plugs reduce operator error.

Support: fast spares, bilingual docs, and retrofit faceplate to match legacy FT cut-outs.

Quality: documented contact plating, cycle life, and IEC 60255 insulation checks per batch.

Send your panel photo + SLD. We’ll return a pole schedule, labeled faceplate, and a sample set (block + plug) for your next FAT.

Final word

If your daily reality is commissioning reliability under tight outages, start with ODES Electric (stocked plugs, labeled plates, and proven MBB CT shorting). For HV projects bundled with domestic panels, shortlist NanZi/XJ/Pinggao; for cost-sensitive OEM runs, add CHINT.

Send your drawing—we’ll map poles, print the faceplate, and ship a ready-to-wire kit.

ODES Electronics