Toughened glass selection guide depends on the users benefit in choosing Orient toughened glass insulators, and the Comparison of tests between ANSI requirements and Orient recommendations are as follows.

Toughened glass selection guide:
Users benefit in choosing Orient toughened glass insulators:
When developing and manufacturing toughened glass insulators, Orient does not limit itself to minimum standard requirements but offers a superior level of performance to its products providing higher safety margins for users.

Comparison of ANSI requirements and Orient recommendations:
Type tests of different type of test:
Test designation:
Thermal-mechanical load- cycle test
Four 24-hour cycles of temperature variation
After the thermal cycles, the insulators are subjected to mechanical test up to breakage.
Residual strength test Mechanical tensile load test on 25 insulator units which have had the shells completely broken off.
Impact test

CSA C411-1 requirements:
Test on 10 units
Temperature range: -50° / +50° C
Applied tensile load: 70% of the rating
Evaluation: X ≥ rating + 3 S
Test on insulators after thermal cycles
Evaluation: X≥ 0.65 x rating + 1.645 S
5 to 10 N-m

ANSI C29-2 requirements:
Test on 10 units
Temperature range: -30° / +40° C
Applied tensile load: 60% of the rating
Evaluation: X ≥ rating + 1.2 S
Evaluation: X≥ 0.6 x rating + 1.645 S
5 to 10 N-m

Recommendations:
Test on 25 units
Temperature range: -50° / +50° C
10 units followed by a steep front wave impulse test: No puncture allowed
Applied tensile load: 70% of the rating
Evaluation: X≥ rating + 3 S
Test on insulators after thermal cycles
Evaluation: X≥ 0.8 x rating + 1.645 S
45 N-m

User benefits:
Higher criteria assure better resistance to ageing even under extreme climatic conditions
High residual strength means that replacement is not urgent and can be safely scheduled.
This results in reduced maintenance costs
High impact strength reduces damages during handling and installation

Type tests of different sample test:
Mechanical failing load test
A mechanical tensile load is applied to insulator up to failure.
Power-frequency puncture test
Evaluation: X≥ rating + 3 S
Individual values ≥ rating
A low frequency voltage is applied to the insulator units immersed in an insulating liquid
Evaluation: X ≥ rating + 1.2 S
S ≤ 1.72 S
A low frequency voltage is applied to the insulator units immersed in an insulating liquid
Evaluation: X≥ rating + 3 S
Individual values ≥ rating
A steep front wave impulse simulating real lightning stress is applied to the insulator units with a peak voltage of 2.8 p.u. (see IEC 61211)
A narrow standard deviation is the result of high quality components and manufacturing; this means enhanced safety and dependability
Guaranty of high puncture strength means less risk of failure under lightning overvoltage
Standard deviation of the test
Average deviation as per ANSI C29.2
Average value of test

String electrical rating for insulator Ø 255-280mm/ 146mm spacing
Critical impulse flashover voltage and Low frequency flashover voltage

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