Load Control Device Miswire Detection Circuit

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Solution Overview

Problem

Existing home automation systems lack effective methods to detect and prevent miswire conditions in load control devices, which can lead to operational failures and potential damage during installation.

Innovation Solution

A load control device configured to detect miswire conditions by using phase-control dimming techniques and multi-location circuits to determine if a hot-to-dimmed-hot, neutral-to-accessory-terminal, accessory-dimmer, or accessory-dimmer-terminal-hot-short miswire exists, maintaining the controllably conductive device non-conductive in such cases to prevent undesired operation and damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If miswire detection functionality is added to the load control device, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvemiswire detection capabilityVSAvoidcontrol circuit complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The control circuit performs miswire detection during the initialization phase before normal operation begins. The device checks for miswire conditions (hot-to-dimmed-hot, neutral-to-accessory-terminal, accessory-dimmer, accessory-dimmer-terminal-hot-short) during startup and only proceeds to normal operation if no miswires are detected, preventing damage before it occurs

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control circuit continuously monitors voltage levels at various terminals (hot terminal, dimmed-hot terminal, accessory terminal) and provides feedback signals to detect miswire conditions. The device compares detected voltage levels against expected values and triggers appropriate responses when deviations indicate miswiring

Inventive Principle:

Principle #23Feedback

2Reliability

If the load control device continuously monitors voltage to detect miswire conditions, then reliability is improved, but energy consumption increases

Engineering Contradiction:

Improvemiswire detection accuracyVSAvoidpower consumption for monitoring

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The control circuit performs voltage monitoring and miswire detection during specific time windows (initialization phase and at defined intervals during operation) rather than continuously. This periodic monitoring approach reduces energy consumption while maintaining detection capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The device conducts miswire detection at periodic intervals during operation rather than continuously monitoring. The control circuit checks for miswire conditions at initialization and at predetermined time intervals, balancing detection reliability with energy conservation

Inventive Principle:

Principle #19Periodic action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution effectively prevents operational failures and damage by accurately detecting miswire conditions and disabling the load control device until the conditions are corrected, ensuring safe and proper installation and operation.

Implementation Method 1

a control circuit configured to control the controllably conductive device using a phase-control dimming technique to control the amount of power delivered to the electrical load

Methodology Applied

Scientific EffectPhase-control dimming:

Implementation Method 2

determine that the first miswire condition exists by detecting if voltage is not present across the controllably conductive device when the controllably conductive device is non-conductive during the second portion of the half cycle

Methodology Applied

Scientific EffectVoltage detection:

Implementation Method 3

The multi-location circuit may be configured to receive an accessory-dimmer voltage at the accessory terminal and scale the accessory-dimmer voltage to generate a multi-location receive voltage

Methodology Applied

Scientific EffectVoltage scaling:

Implementation Method 4

determine that the second miswire condition exists by detecting if voltage is present at the accessory terminal in a negative half cycle of the AC power source in response to the multi-location signal

Methodology Applied

Scientific EffectVoltage detection:

Implementation Method 5

The control circuit may be configured to sample the multi-location signal to determine if the second miswire condition exists, and to discharge voltage developed on wiring connected to the accessory terminal due to capacitance of the wiring while the control circuit is sampling the multi-location signal

Methodology Applied

Scientific EffectCapacitance discharge: Capacitance

Data Source

PatentUS20250004068A1Load control device having miswire detection

Publication Date: 2025.01.02 LUTRON TECHNOLOGY COMPANY LLC

AI summary

A load control device for controlling an amount of power delivered from an alternating-current (AC) power source to an electrical load may be configured to determine if a miswire condition exists at the load control device. For example, a control circuit of the load control device may be configured to detect a hot-to-dimmed-hot miswire condition in which a dimmed-hot terminal may be coupled to a hot side of the AC power source and a hot terminal may be coupled to the electrical load. In addition, the control circuit may be configured to detect a neutral-to-accessory-terminal miswire condition in which the hot terminal may be coupled to the hot side of the AC power source and an accessory terminal may be coupled to a neutral side of the AC power source. The control circuit may maintain a controllably conductive device non-conductive in response to determining that one of the miswire condition exists.