Overcycling at max power – here’s how BLOX helps protect non-cycling tubes

September 30, 2025

The HP11 is one of the most widely used tubes in the field. Despite its popularity, it has notable limitations. By default the HP11 is a non-cycling tube, but with the right setup it can be operated in cycling mode. That means operators must respect a clear trade-off between maximum power and the allowable number of exposure cycles. Too often, we see systems running at full power while cycling far beyond safe limits. The result? Accelerated wear, premature failures, and higher costs.

With BLOX, OEMs, service teams, and end users gain the visibility they need to track cycles accurately, detect overuse, and protect the long-term health of their tubes.

Issue & cause

Non-cycling tubes like the HP11 are designed for specific usage profiles. The trade-off is straightforward:

  • Full nominal power, but limited to 15 cycles per day or 3,000 cycles per year
  • 20% reduced nominal power, which allows significantly more daily cycles

But in practice, many users push past these limits without realizing it.

A “cycle” is defined as either:

  • Switching "high voltage" on/off (one exposure), or
  • Making significant setpoint changes while "high voltage" remains on (dynamic cycles).

Every cycle places thermal and mechanical stress on the tube. When cycles pile up, especially at full power, damage accelerates. Over time, this leads to target deterioration, dose loss, longer exposure times, and reduced throughput.

Cycle chart: Evolution of the cycles (exposures and dynamic cycles) over time

How to spot it

Manually counting cycles is nearly impossible. That’s where BLOX comes in.

  • The Cycles chart tracks cycles per day and flags when daily or yearly limits are exceeded. Each black-box indicator highlights the use of a non-cycling tube.
  • The Power chart shows whether the tube is being run at full or reduced power, giving service teams critical context for cycle counts.

In one real case, a customer ran their HP11 at maximum power and quickly exceeded the 15-cycle daily limit (horizontal red line). BLOX flagged the issue immediately. Later, the same system hit the 3,000-cycle yearly threshold well ahead of schedule (vertical red line). Guided by this data, the service team was able to recommend reducing power by 20% - extending the tube’s usable life.

Power chart: The power used for each exposure over time

Consequences

Overcycling at full power creates cumulative damage that shortens tube life and impacts system reliability. The most common effects are:

  • Thermal stress on the target, leading to dose loss and degraded image quality
  • Longer exposure times as the system compensates for dose loss
  • Reduced the throughput of inspected objects
  • Added strain on the generator and high-voltage cable
  • Premature tube replacement and unplanned downtime

For production-critical systems, these impacts translate directly into lost revenue and reduced customer satisfaction.

Before thermal stres
After thermal stress
Before thermal stress
Gradual dose loss caused by thermal stress
Advanced dose loss caused by thermal stress

Recommendations

When BLOX indicates overcycling of a non-cycling tube, the best response is to act quickly:

  • Engage the end-user to adapt operating modes (an option would be to use mechanical shutters) and respect cycle and power limits
  • Offer a cycling-capable tube (such as UP or XP models) that matches the workload more effectively
  • Keep spares in stock if usage patterns cannot be changed, ensuring uptime even if premature failures occur

The HP11 is a powerful and proven tube, but like all non-cycling models, it must be used within its limits. BLOX makes those limits clear by tracking cycles automatically and flagging when thresholds are exceeded. With this insight, OEMs, service teams, and users can collaborate to extend tube life, reduce costs, and safeguard system uptime.

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