Okay, I understand. You're trying to find the time-current curves for a GE TLB1 circuit breaker for full testing and are running into a dead end. "Megging" (insulation resistance testing) is important, but doesn't fully characterize the breaker's operational performance. Here's a breakdown of potential solutions and things to consider

Why the Difficulty in Finding TLB1 Curves:
Older Breaker & Limited Production

The TLB1, being an older and potentially less common model than the TLB2 and TLB4, might not have had its curves widely distributed. It's possible it was a specific OEM product or a very limited production run.

Proprietary Information

GE (now GE Vernova, though this likely predates that split) might have considered the detailed curves proprietary information not intended for public release, especially for end-users. They would have provided this information primarily to panelboard and switchboard manufacturers for coordination studies.

Lost to Time

Documents can simply be lost or destroyed over the years, especially for products from the 1980s.

Curves Possibly Combined with TLB2

The performance characteristics of the TLB1 may be nearly identical to a similar Ampere rating of the TLB2.

Steps to Take & Things to Try


Contact GE Vernova/Current

This is your best initial approach. Go to the GE Vernova website (or the website of the current GE group responsible for electrical distribution equipment). Look for a "Contact Us" or "Support" section. Explain that you need the time-current curves for a TLB1 circuit breaker and are having difficulty finding them in publicly available documentation. They may have a historical archive or a product specialist who can help. Be polite and persistent. Provide them with all relevant information: voltage rating, amperage rating, catalog number (if you have it), any markings on the breaker.2.

Re-Examine Your Resources More Closely



Check for Sub-Models/Variations

Are there any other markings on the breaker besides "TLB1"? There might be a suffix or prefix that indicates a specific sub-model or variation. This could lead to a more specific search term.

Look for Application Guides

Sometimes, application guides for panelboards or switchboards that used TLB breakers will include representative curves for different breaker types. They might not be specific to the TLB1, but they could give you a reasonable approximation.

Examine the Breaker's Label Carefully

The label might have an instantaneous trip setting marked on it. This provides at least one point on the curve.3.

Consider Testing the Breaker Yourself (Carefully and Safely)

This is the most direct, but also the most involved and potentially dangerous, approach.

Only do this if you are qualified and experienced in testing circuit breakers and have access to appropriate equipment. High-Current Test Set

You'll need a high-current test set capable of delivering several times the breaker's rated current.

Controlled Environment

Conduct the tests in a safe, controlled environment with appropriate safety measures.

Data Acquisition

Accurately measure the current and the time to trip for several different current levels. Document everything thoroughly.

Plot the Curve

Use the data you collect to plot the time-current curve.

Calibration and Safety

The testing device should be recently calibrated, and the voltage ratings must be checked.

DO NOT TEST ON CRITICAL EQUIPMENT! Breakers can fail after testing. The purpose of testing is to evaluate the breaker's behavior, and this can be destructive. RISK OF ARC FLASH

Be aware of arc flash hazards. Testing high-current devices can generate significant arc flash energy. Use appropriate personal protective equipment (PPE).4.

Consult with Electrical Engineers/Testing Companies



Power Systems Engineers

Consult with a power systems engineer experienced in protective device coordination. They might have access to databases or software that include the TLB1 curves or could help you estimate them based on similar breakers.

Electrical Testing Companies

Companies that specialize in testing and maintaining electrical equipment might have experience with TLB breakers and access to the curves or have the equipment to test the breaker yourself.5.

Cross-Reference with Other Manufacturers

Sometimes, GE may have had a cross-licensing agreement with another manufacturer for circuit breaker technology. Research other breaker manufacturers from that era (e.g., Westinghouse, Square D) and see if they had similar breaker models. The performance characteristics might be comparable. Use Tra-Ser with as many cross-references as possible to find equivalent parts or breakers.6.

Extrapolate from TLB2 and TLB4 Data (With Caution)

If you can't find the TLB1 curve, you might be able to extrapolate or interpolate a curve based on the TLB2 and TLB4 curves, particularly if you know the ampere rating and any other specific characteristics of the TLB1. However, this should be done with extreme caution and only as a last resort. The TLB1 might have significantly different trip characteristics.7.

Check Online Electrical Forums

Post your query on relevant electrical engineering forums or groups (e.g., on LinkedIn, Reddit, or specialized electrical engineering websites). Someone might have the curve or know where to find it.

Important Considerations



Age and Condition

Keep in mind that a breaker from 1989 is quite old. Even if you find the original curves, the breaker's actual performance might have drifted due to aging, wear, or previous faults.

Testing vs. Coordination

Testing a breaker is different from performing a full coordination study. A coordination study requires considering all the protective devices in a system to ensure proper selectivity and minimize outages.

Safety First

Always prioritize safety when working with electrical equipment. If you're not comfortable with any of these steps, consult with a qualified electrical professional.*

Documentation: Keep detailed records of all your research, testing, and any assumptions you make.Good luck! It's a challenging task, but hopefully, one of these approaches will lead you to the information you need. Flag for review