Short Answer
Both DC LVITs and AC LVDTs are inductive, contactless linear position sensors, but they differ primarily in signal format, required electronics, and system integration.
- DC LVITs provide a direct, conditioned DC output (such as 0–5 V, 0–10 V, or 4–20 mA)
- AC LVDTs produce a raw AC signal that typically requires external signal conditioning
How Do Their Outputs Differ?
A DC LVIT (Linear Variable Inductance Transducer) includes internal electronics that convert the inductive sensing signal into a usable DC output. This means it can be connected directly to:
- PLC analog inputs
- Data acquisition systems
- Industrial controllers
An AC LVDT (Linear Variable Differential Transformer) generates an AC output signal that must be:
- Excited with an AC source
- Demodulated and conditioned by external electronics such as an AC LVDT Signal Conditioner
This additional step allows flexibility, but adds complexity to the system.
What About Signal Conditioning?
- DC LVIT:
- Signal conditioning is built into the sensor
- Outputs a ready-to-use DC signal
- Simplifies wiring and system design
- AC LVDT:
- Requires an external signal conditioner (or controller with built-in LVDT input)
- More components, but greater flexibility in tuning and configuration
How Do They Compare in Installation and Integration?
DC LVITs are typically easier to integrate:
- No external signal conditioner required
- Fewer components and connections
- Faster setup in industrial environments
AC LVDTs require more setup:
- External electronics must be selected and configured
- Excitation frequency and scaling may need adjustment
- More wiring between sensor and conditioner
Are There Differences in Performance?
Both technologies offer:
- Contactless operation (no wear)
- High repeatability
- Long service life
However, there are some distinctions:
- AC LVDTs are often preferred in high-precision or laboratory applications where signal conditioning can be optimized externally
- DC LVITs are commonly used in industrial environments where simplicity, ruggedness, and ease of integration are priorities
What About Environmental Considerations?
Both LVITs and LVDTs are well-suited for harsh environments, but:
- DC LVITs integrate electronics inside the sensor body, which must be rated for the operating environment
- AC LVDTs can keep electronics remote from heat, vibration, or contamination by using a separate signal conditioner
When Should I Choose a DC LVIT?
A DC LVIT is typically the better choice when you want:
- A simple, plug-and-play installation
- A direct analog output compatible with standard control systems
- Reduced wiring and fewer external components
When Should I Choose an AC LVDT?
An AC LVDT is often preferred when you need:
- Flexible signal conditioning or custom scaling
- Electronics located away from harsh environments
- Integration with existing LVDT signal conditioning systems
Bottom Line
Both DC LVITs and AC LVDTs provide reliable, contactless position measurement.
The key difference is how the signal is delivered:
- DC LVIT → Integrated electronics, direct DC output, easier integration
- AC LVDT → Raw AC signal, external conditioning required, more flexible system design
Choosing between them depends on your application requirements, system architecture, and environmental conditions.