Energizer Calculation Information
Disclaimer for Voltage Decay Calculations
The voltage decay calculations provided in these tables are based on practical estimations for a variety of electric fence energizers rated for 5, 10, 25, 50, and 100 miles of fence. These calculations assume real-world conditions and take into account factors like wire resistance, energizer joule rating, and the inherent limitations of electric fence systems when pushed beyond their advertised capacities.
The results provided are approximations and should be used as general guidelines. Actual performance may vary based on specific field conditions, energizer quality, and environmental factors. The following key assumptions and practical considerations were used to calculate the voltage decay over distance.
Key Assumptions and Factors Used in the Voltage Decay Calculations:
- Energizer Rating:
- The calculations assume standard electric fence energizers with rated capacities of 5, 10, 25, 50, and 100 miles. Each energizer has a different initial voltage and joule rating (pulse energy), which dictates how much energy can be delivered per pulse.
- Starting voltages for these energizers typically range from 5000V to 13,000V, depending on the energizer model.
- Wire Resistance:
- For each setup, we assume 3 strands of wire in parallel, with resistance per mile typically set at 0.02 ohms per mile per strand.
- With 3 strands, the effective resistance per mile is calculated by dividing the resistance by 3 which is the number of strands used in this exercise.
- This low resistance is typical of high-quality electric fence wiring but is still subject to voltage loss over long distances.
- Practical Voltage Loss:
- Voltage decay is not a purely linear function of resistance; it is impacted by the energizer's ability to maintain voltage over long distances and real-world inefficiencies. To account for these practical issues, the following voltage loss rates are applied:
- 10% voltage loss per mile within the energizer’s rated distance.
- 15% voltage loss per mile beyond the rated distance for energizers exceeding their intended capacity.
- As the distance increases (beyond 25 miles, for example), voltage loss may accelerate to 20% per mile or more, depending on the specific energizer and environmental factors.
- Environmental Factors:
- Voltage decay can be significantly impacted by environmental conditions such as:
- Vegetation touching the wire, drawing current away from the fence.
- Poor grounding systems that prevent the fence from completing its electrical circuit effectively.
- Impedance mismatches due to inconsistent fence construction or poor connections.
- These factors are inherently difficult to quantify exactly and can cause voltage to decay faster than expected.
- Joule Ratings:
- The joule rating of an energizer, which defines the total energy delivered in each pulse, is a crucial factor. A higher joule rating generally allows the energizer to maintain voltage over longer distances.
- For example:
- A 5-mile energizer might have around 1-2 joules of energy per pulse.
- A 10-mile energizer might deliver 2-4 joules.
- 25- and 50-mile energizers may have 5-10 joules.
- A 100-mile energizer could deliver 10-15 joules or more.
- Distance vs. Advertised Rating:
- Energizer ratings (e.g., 5 miles, 10 miles) represent the manufacturer’s suggested optimal distance for effective voltage retention. However, advertised distances often assume ideal conditions (no vegetation, perfect grounding, etc.). In practice, voltage can decay more quickly due to resistance and the above-mentioned inefficiencies.
- Beyond the rated distance, voltage loss accelerates as the energizer struggles to deliver the necessary pulse energy to the wire.
Voltage Decay Practical Application
- The voltage decay estimates provided in the tables reflect how real-world performance differs from theoretical values. These calculations are intended to help users understand how energizer performance diminishes over long distances and what to expect when a fence setup exceeds the energizer's advertised rating.
- For larger energizers (e.g., 25-mile or 50-mile units), voltage decay will happen more slowly over longer distances, but beyond their rated capacity, they too will experience significant voltage losses, especially when combined with environmental challenges.
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Voltage decay will vary based on the resistance of each wire gauge. Thicker wires (lower gauge numbers) will result in slower voltage loss over distance compared to thinner wires (higher gauge numbers).
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The 3-strand setup reduces the effective resistance by dividing the total resistance by 3, but voltage decay beyond the rated energizer distance remains significant, particularly for longer distances and higher resistance wire gauges.
Key Considerations for Different Wire Gauges:
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Resistance per Mile: Wire gauge significantly affects the resistance of the wire, and hence, the voltage drop over distance. Thicker wires have lower resistance and retain voltage better over long distances.
Here's the typical resistance per mile for different wire gauges: - 5 mil wire: 167 ohms/mile
- 6 mil wire: 150 ohms/mile
- 7 mil wire: 133 ohms/mile
- 8 mil wire: 117 ohms/mile
- 9 mil wire: 107 ohms/mile
- 10 mil wire: 100 ohms/mile
- 12 mil wire: 83 ohms/mile
- Effective Resistance for 3 Strands: Since the system uses 3 strands, the total resistance will be divided by 3.
Joule Averages for Exercise
The joules averages used for this exercise:
- 2-mile energizer: 0.1 joules
- 5-mile energizer: 0.5 joules
- 10-mile energizer: 1 joule
- 25-mile energizer: 2 joules
- 50-mile energizer: 3 joules
- 100-mile energizer: 6.3+ joules
Conclusion
These calculations are designed to provide practical guidance for users setting up electric fences over various distances using energizers with different ratings (5-mile, 10-mile, 25-mile, 50-mile, and 100-mile). While the estimates are grounded in typical real-world conditions, actual voltage performance should always be tested in the field using a fence voltmeter, as local environmental factors and fence quality can impact results.