Compressor Grid Fault Detection for Thermal Overload Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Compressors connected to an electrical grid experience rapid current increases due to voltage drops during grid faults, leading to potential stalling and thermal overload, which can cause cascading issues in the grid and make it difficult to mitigate low voltage events.
Innovation Solution
A compressor monitoring system that includes current and voltage monitors, averaging modules, and a control module to detect grid faults by calculating ratios of average current and voltage values, generating fault signals when thresholds are exceeded, and deactivating the motor to prevent damage and stabilize the grid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the compressor continues to operate during grid voltage drops, then the compressor can maintain continuous operation, but the current increases dramatically causing thermal overload and potential damage
Solution Approach 1:
The system performs preliminary detection of grid voltage conditions and predicts current increases before thermal damage occurs. The fault detection device monitors voltage drops and calculates expected current values in advance, allowing the compressor to be deactivated before thermal overload damages the motor or compressor components.
Solution Approach 2:
The system continuously monitors grid voltage and compressor current, comparing actual measurements against predicted values. When the feedback shows current exceeding safe thresholds due to voltage drops, the control device adjusts operation by deactivating the compressor to prevent thermal overload.
2Reliability
If the compressor is deactivated during grid faults, then thermal overload is prevented, but continuous operation is interrupted
Solution Approach 1:
The system uses continuous feedback monitoring of grid voltage and compressor performance to determine when deactivation is necessary. By comparing actual current measurements against predicted safe operating values, the system intelligently decides when to interrupt operation to prevent damage, balancing reliability with continuity.
Solution Approach 2:
The system changes operational parameters (voltage thresholds, current limits, time delays) to optimize the balance between preventing damage and maintaining continuity. By adjusting these parameters, the system can be tuned to allow operation during minor voltage fluctuations while deactivating only during severe faults that would cause thermal overload.
3Device complexity
If simple current threshold monitoring is used, then the detection system is simple, but it cannot distinguish between startup current and fault current
Solution Approach 1:
The system performs preliminary calculations of expected current values based on measured grid voltage and compressor operating conditions. By establishing what the current should be under normal conditions before making fault determinations, the system can accurately distinguish between normal startup current and dangerous fault current without requiring complex hardware.
Solution Approach 2:
The system introduces an intermediate calculation step that predicts expected current based on voltage measurements and operating parameters. This intermediary prediction acts as a reference against which actual current is compared, enabling accurate fault detection while keeping the physical detection system simple and inexpensive.
Data Source
Figure 1A~1B
Figure 2~3
Figure 4
AI summary
A compressor monitoring system includes current and voltage monitors, current and voltage averaging modules, a control module, and a switch. The current monitor measures a current drawn by a motor of a compressor. The current averaging module generates first and second average current values based on the current measured by the current monitor. The voltage monitor measures a utility power voltage. The voltage averaging module generates first and second average voltage values based on the voltage measured by the voltage monitor. The control module selectively generates a fault signal when a first ratio is greater than a first predetermined threshold and a second ratio is less than a second predetermined threshold. The first ratio is based on the first and second average current values. The second ratio is based on the first and second average voltage values. The switch deactivates the motor when the fault signal is generated.