Insulator Routine Tensile Testing Machine (Semi Tensile Machine) 600 kN for Ceramic & Glass Disc Insulators — IEC 60383-1 Clause 31

Insulator routine tensile testing machine at a glance

• Purpose: the routine mechanical test of IEC 60383-1 Clause 31 — a tensile load of 50% of the specified mechanical load (SML) applied and held on every unit that comes off the line.
• Capacity: 600 kN maximum tensile load with ±1% accuracy; one unit per test.
• Specimens: ceramic and glass disc insulators with ball and socket fittings, section length 100 – 340 mm.
• Cycle: load ramps to the set value, the PLC holds it for the preset dwell time of 0 – 60 s, then releases; the unit is accepted if it survived without fracture or slippage.
• Control: PLC with keyboard and screen; the applied load and the dwell countdown are shown, so the verdict is clear.
• Build: hydraulic cylinder with a 200 mm stroke, welded and machined rigid frame, connector screw M75 x 3-6g.

1. What this machine is used for

After insulators come off the production line, every single unit has to pass the routine mechanical test, in which a tensile load equal to 50% of the specified mechanical load (SML) is applied and held. That is the acceptance requirement of IEC 60383-1 Clause 31, Routine mechanical test, and of 31.2, Routine mechanical test on string insulator units.

One insulator unit is fitted between the ball and socket fixtures, the hydraulic cylinder applies the routine test load, and the PLC holds the load for the preset dwell time. Units that survive the hold without fracture or slippage are accepted; any unit that fails is rejected before it can enter the finished goods stock.

The compact horizontal layout and the 200 mm cylinder stroke make loading and unloading fast, so the machine keeps up with the rhythm of line-side inspection. For a 120 kN disc insulator the test load is a 60 kN hold on every single unit — a load level that only a dedicated, rigid, hydraulically powered machine can deliver safely at production line speed.

2. Standards applied

• IEC 60383-1:2023 – Clause 31 Routine mechanical test, in particular 31.2 Routine mechanical test on string insulator units (routine tensile load = 50% of the specified electromechanical failing load for cap and pin units).
• GB/T 1001.1 – Ceramic or glass insulator units for a.c. systems – definitions, test methods and acceptance criteria, including the routine tensile test requirement.
• Related tests – the same standard defines the type and sample tests, which are run on separate machines; this machine is dedicated to the 100% routine screening.

3. Technical parameters

The routine test load is set per unit rating: 50% of the specified electromechanical failing load of the disc insulator under IEC 60383-1. A hydraulic power unit with a load holding valve keeps the set load stable for the whole dwell time, and the dwell time, the ramp rate and the pass / fail indication are configured from the PLC screen.

4. Key functions

• Semi-automatic cycle: the operator loads the insulator and starts the cycle, and the machine ramps, holds and releases automatically under PLC control.
• Load held stable for the whole dwell time by a hydraulic power unit with a load holding valve.
• Dwell time adjustable from 0 to 60 s, ramp rate and pass / fail indication configured from the screen; the applied load and the dwell countdown are displayed.
• Fast changeover: ball and socket fixtures accept the common disc fitting sizes and the 200 mm stroke covers section lengths from 100 mm to 340 mm without shimming.
• Rigid welded and machined frame, so the elastic storage is minimised and the load shown at the transducer is the load the insulator actually sees.
• Load applied to ±1% accuracy up to 600 kN, so the pass / fail decision is trustworthy and traceable.

5. Typical applications

• Ceramic and toughened glass disc insulator manufacturers – 100% routine inspection after the firing or tempering line.
• Insulator test laboratories – verification of the routine test requirement of IEC 60383-1 Clause 31 on behalf of a manufacturer.
• Utility and trader incoming inspection – re-verification of batches of disc insulators before installation.
• Production quality control – screening out units with a latent defect before they reach the finished goods stock.

6. Frequently asked questions

1. Why 50% of the specified mechanical load?

Because that is what IEC 60383-1 Clause 31.2 specifies for the routine mechanical test on string insulator units: each unit is subjected to a tensile load of 50% of its specified electromechanical or mechanical failing load. For a 120 kN disc insulator that is a 60 kN hold on every single unit.

2. Is this a type test machine or a production machine?

It is a routine test machine for the production line. It applies and holds the 50% SML load on every unit that comes off the line, and it is built for speed and repeatability. The type and sample tests, which load the unit to failure, are run on separate tensile testing machines.

3. How long is the load held?

The dwell time is set on the screen from 0 to 60 s. The hydraulic power unit has a load holding valve, so the set load stays stable for the whole dwell time.

4. Which insulator sizes does the machine take?

One unit per test, with ball and socket fittings, and a section length from 100 mm to 340 mm. The 200 mm cylinder stroke covers that range without shimming. Fixture sets for other coupling sizes can be supplied.

5. Why is the frame rigidity important?

Because a frame that stores energy elastically shows a load at the transducer that is not the load the insulator sees. The welded and machined frame of this machine minimises that elastic storage, so the displayed load is the load on the unit and the pass / fail decision is trustworthy.

6. Can the machine be supplied with a different load rating or with data logging?

Yes. Fixture sets for other coupling sizes, data logging of every test cycle for quality traceability, and load ratings other than 600 kN can be configured on request. Contact CONTUNE INTERNATIONAL CO.,LTD with the coupling distance and the SML rating of the insulator for a tailored proposal.

Related insulator mechanical test equipment

The test that loads a unit to failure is run on the horizontal tensile testing machine, the dimensions are checked on the deviation checking device for disc insulator units, and the combined load and temperature test on the thermal-mechanical stress testing machine. The complete range is listed under insulator test equipment.