Demand Forgiveness Causes Unintended Impact on Sliding Demand and kVAh Energy Calculations in ION8650 Meters
Issue
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Product Line
ION8650 series meters
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Environment
ION Setup
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Cause
Demand Forgiveness is designed to prevent demand calculations during a configurable period following power restoration. During the configured Demand Forgiveness interval, the demand calculation inputs are intentionally forced to zero. This behavior is expected and is part of the Demand Forgiveness design.
However, two additional unintended framework behaviors may occur:
- Sliding Window Demand calculations may not resume correctly after the Demand Forgiveness interval expires.
- kVAh energy accumulation may be interrupted during the Demand Forgiveness period, resulting in lower-than-expected kVAh values.
For utility and revenue applications, these behaviors originate from the factory ION framework implementation and are not caused by a meter hardware failure. As a result, demand and energy values may be affected, which can impact billing calculations.
When Demand Forgiveness suppresses these Arithmetic module outputs, both of the following are affected:
- Sliding Window Demand calculations
- kVAh energy accumulation
The kWh and kVARh integrators are not affected because they are supplied by different Arithmetic module outputs.
As a result, Counter Module #40 does not reset correctly, preventing normal demand operation from resuming.
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Solution
As shown in the image below, select Show Connections for Arithmetic Module #4. The connection report shows that the module supplies both the Sliding Window Demand modules and the kVAh Integrator modules.
The Demand Forgiveness logic in the existing Arithmetic formulas therefore affects both kVA demand and kVAh energy.
To separate the calculations:
- Open Arithmetic Module #4 in ION Setup.
- Under Setup Registers, add equivalent kVA calculations to unused formulas, such as ART4 Formula 5 through ART4 Formula 8, without the Demand Forgiveness conditions.
- Leave the Sliding Window Demand modules connected to the existing Demand Forgiveness-controlled outputs.
- Unlink the applicable kVAh Integrator modules from their original Arithmetic outputs.
- Link the kVAh Integrator modules to the new Arithmetic outputs that do not contain the Demand Forgiveness conditions.
- Verify each connection by selecting Show Connections.
In the example shown:
- The Sliding Window Demand modules remain connected to the original named outputs.
- The applicable kVAh Integrator modules are moved to ART4 Result 5 through ART4 Result 8.
- The new output registers may retain their default names unless they are renamed as part of the implementation.
After this modification:
- Demand Forgiveness continues to suppress demand calculations during the configured forgiveness period.
- kVAh energy accumulation continues independently of the Demand Forgiveness algorithm.
- kVAh values continue to represent measured energy during the forgiveness interval.
Workaround B - Correct Demand Forgiveness Demand Behavior
Add a reset-pulse path so that Counter Module #40 receives the required Reset trigger.
Create the following modules:
- One Feedback module
- One One-Shot Timer module
Configure the framework as follows:
- Link the Delay Reset output of Pulse Merge Module #36 to the Source input of the new Feedback module.
- Link the Pulse Output of the Feedback module to the Start input of the new One-Shot Timer module.
- Configure the One-Shot Timer duration as 1 second.
- Link the Trigger output of the One-Shot Timer module to the Reset input of Counter Module #40, labeled Delay Time.
Both workarounds must be applied:
- Workaround A prevents the Demand Forgiveness logic from interrupting kVAh energy accumulation.
- Workaround B ensures that Sliding Window Demand operation resumes correctly after the Demand Forgiveness interval.
Applying only Workaround B corrects the demand-recovery behavior, but it does not prevent the interruption of kVAh accumulation described in Workaround A.
After both modifications are applied:
- Demand Forgiveness continues to operate during the configured interval.
- Sliding Window Demand calculations resume correctly after the interval.
- kVAh energy accumulation continues during the forgiveness period.
- Billing-related kVAh energy accumulation is no longer interrupted by the Demand Forgiveness logic.