Ammeters used in cathodic protection need to have what type of resistance?

Ammeters used in cathodic protection systems are designed to have low resistance. This characteristic is crucial because the purpose of the ammeter is to measure the current flowing through a circuit created by the cathodic protection system, typically involving the flow of corrosion protection current to a metal structure.

When measuring current, low resistance in the ammeter ensures that it does not significantly impede the current flow in the circuit being tested. If the ammeter had high resistance, it would alter the current flow, leading to inaccurate measurements and unreliable data regarding the effectiveness of the cathodic protection system. Therefore, utilizing a low-resistance ammeter allows for precise monitoring of the current, essential for evaluating the performance of cathodic protection installations.

In contrast, high resistance would result in voltage drops and potentially misleading conclusions about the system's performance. Variable resistance would complicate the measurement process without providing the clear, direct readings required. Lastly, an ammeter with no resistance would be impractical, as it would not function correctly and would lack the ability to measure current accurately.