How Rockwill RVR AVR and SVR Medium Voltage Line Regulators Differ？

• AVR (Automatic Voltage Regulator). In medium voltage line applications, the term denotes the functional category of automatic step voltage regulators. Rockwill single-phase literature refers to it as an AVR Step Voltage Regulator, rated 2.4 to 35 kV, with 32 steps of approximately five-eighths of a percent (0.625 percent) and a total range of ±10 percent, available to ANSI C57.15 or IEC requirements. Note that in low-voltage and generator applications, AVR may also mean an excitation regulator or a thyristor-based voltage stabilizer, and that meaning must not be confused with medium voltage on-load regulation.

• RVR (Rockwill Voltage Regulator). Rockwill's on-load step voltage regulator series. The RVR-1 is single-phase and the RVR-3 is three-phase, both supplied with an RVR smart controller that provides line drop compensation, setpoint, bandwidth and time delay settings, overcurrent and undervoltage blocking, and optional communication.

• SVR (Step Voltage Regulator / Feeder Voltage Regulator). Rockwill's three-phase page uses the SVR-3 as the feeder automatic voltage regulator model, comprising an autotransformer, an OLTC, an SVR smart controller, and current and voltage transformers. In the wider industry the term is also used generically for a line automatic voltage regulator, tending to imply three-phase feeders, substation outgoing feeders, and heavier loads.

1. How to Choose Between the Single-Phase RVR-1 and the Three-Phase RVR-3？

The RVR-1 is a single-phase oil-immersed autotransformer on-load regulator, suited to pole-mounted single-phase feeders and single-phase laterals, or to three-unit open-delta banks on three-phase three-wire systems. The RVR-3 is a complete three-phase oil-immersed unit, suited to three-phase distribution networks and to substation, pad-mounted, or pole-mounted installation.

Key takeaway: use the RVR-1 for fine-grain correction at the end of single-phase laterals (0.625 percent per step), and use the RVR-3 when a three-phase application calls for a wide range (2.5 percent per step, ±20 percent).

2. Are the SVR-3 and the RVR-3 the Same Product, and Where Do Their Specifications Overlap？

On Rockwill's official three-phase pages, the SVR-3 and the RVR-3 are both presented as three-phase automatic step voltage regulators. Their core architecture is the same: an oil-immersed autotransformer, a motor-driven OLTC, current and voltage transformers, and a smart controller. Both offer a regulation range of up to 16 steps × 2.5 percent, ±20 percent. The differences are mainly the series name used on the page and the orderable voltage matrix.

• RVR-3 official listing: 13.8 / 14.4 / 19.92 / 34.5 kV, 38 to 1000 kVA, with IEC 60076-21, IEC 60214, IEEE C57.15, and similar standards applicable.

Three-Phase Automatic Step Voltage Regulator

• SVR-3 catalogue: separately lists 50 Hz voltages of 6 / 6.35 / 11 / 15 / 22 / 33 kV and 60 Hz voltages of 7.62 / 13.8 / 14.4 / 19.92 / 34.5 kV. One technical table lists rated currents of 50 to 1665 A, capacities of 38.1 to 1000 kVA, and a basic impulse level (BIL) of 60 to 200 kV, depending on model and voltage class. Its controller is designated the SVR smart controller and supports GPRS, GSM, and Bluetooth, together with overcurrent, overload, undervoltage, and fault blocking functions.

• Recommended tender wording: do not write only "SVR". Write instead "three-phase medium voltage on-load step voltage regulator, autotransformer plus OLTC, 16 × 2.5 percent or taps selected to suit the load, oil-immersed ONAN, controller with line drop compensation, bandwidth, time delay and limits, and communication protocol".

3. Mapping Medium Voltage AVR RVR and SVR to a Concrete Selection

Match the choice directly to the feeder conditions.

1. Single-phase long laterals, end-of-line correction from a pole, fine tap steps required: RVR-1 or AVR step, 32 × 0.625 percent, ±10 percent.

2. Three-phase distribution, substation outgoing feeders, severe end-of-line undervoltage, ±20 percent required: RVR-3 or SVR-3, 16 × 2.5 percent.

3. Tender specifies only the function and does not fix a model: use "AVR / medium voltage on-load step voltage regulator" as the generic category name, then lock the phase count, voltage, current, tap steps, OLTC, and controller communication of the RVR or SVR in the technical data table.

4. PV and distributed generation, where reverse overvoltage is a concern: first confirm whether the specific controller supports reverse regulation, generation coordination, or bidirectional setpoints. Rockwill's RVR-1 literature emphasizes closed-loop voltage and current sensing with automatic tap changing, but whether forward, reverse, or coordinated operation is supported must be confirmed against the ordered controller model and the type test report. It is not standard across the entire range by default.

4. Why None of Them Is a Thyristor Regulator or an SVC STATCOM？

The RVR, AVR step, and SVR medium voltage on-load solutions change taps by driving a tap changer with a motor. They are step-type on-load regulators that operate tap by tap on a second-level timescale and rely on bandwidth plus time delay to prevent oscillation.

They do not provide millisecond-level dynamic voltage support. Where the requirement is voltage sag or flicker mitigation, or transient reactive power support for renewable generation, static reactive compensation, a dynamic voltage restorer (DVR), or a STATCOM should be specified separately. An on-load regulator should not be used as a dynamic compensator.

Overseas distribution network site: Three-phase RVR‑3/SVR‑3 MV line voltage regulators on foundation, commissioned for end-of-long-feeder voltage management.

Edited From：Garca