MFC-201/R Voltage Regulator

Manuals

• Technical Manual (English, PDF)
• Technical Manual (Portuguese, PDF)

Best practices for installation

• The Benefits of Applying IEC 61000-5-2 to Cable Screen Bonding and Earthing
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The articles above were written by Keith Armstrong from Cherry Clough Consultants.

• 80-265V universal power supply
• Full galvanic isolation
• IP20 rated enclosure
• 35 mm DIN rail assembly
• Operation at up to 70°C

Inputs
V_AC: 0-200V, I_AC: 0-5A.

Error/Non-Linearity
0.5% + 0.1% / 10 °C F.S.

Interfaces
RS485, optically isolated (≥ 1.5 kV, 60 Hz, 1 min.), with MODBUS or DNP3 protocol support.

Analog Outputs
Software configurable current loop: 0-1, 0-5, 0-10, 0-20 or 4-20 mA. Isolated outputs (≥ 1.5 kV, 60 Hz, 1 min.).

Relays
2 relays for tap changer commands (raise, lower), 3 relays for alarms (undervoltage, overvoltage, overcurrent). Switching capacity of at least 5A x 250 Vac or 0.5A x 125 Vdc. Galvanic isolation ≥ 1.5 kV (60 Hz, 1 min.).

Display
2 lines, 16 characters each (5 mm). LCD with backlight.

The MFC-201/R was developed to provide the user with the greatest possible flexiblity, such that all supervision and configuration can be executed on-site or remotely through the existing communication channels.

Of all the software configurable parameters, we highlight the following:

Regulation Set (1 to 8)
Selects which set of regulation parameters to configure. A regulation set is composed of the Regulation Menu parameters, associated to a daily time interval.

Nominal Voltage (80 to 140V)
Optimal voltage value at the load, referenced to the PT's secondary. Ignoring any line drop, the load's voltage will match the PT's primary voltage.

Bandwidth (0 to 10%)
Allowable deviation between the measured and nominal voltage. Deviations greater than the bandwidth trigger the tap changer command timer.

Delay Type (Constant, Inverse)
The regulation delay's purpose is to reduce the influence of brief voltage fluctuations, eliminating unnecessary tap changes. The MFC-201/R implements two types of delays:

• Constant, where the interval between the detection of a large enough deviation (as defined by the Bandwidth parameter) and a tap change is fixed, and given by the parameters Raise Delay and Lower Delay.
• Inverse, where the interval between the detection of a large enough deviation (as defined by the Bandwidth parameter) and a tap change is inversely proportional to the deviation's magnitude. In other words, this option produces faster corrections to larger deviations.

Raise Delay (0 to 180 s)
Delay between a deviation that exceeds the bandwidth and the first "raise" command.

Lower Delay (0 to 180 s)
Delay between a deviation that exceeds the bandwidth and the first "lower" command.

Repetition Delay (0 to 30 s)
Delay between consecutive "raise" or "lower" commands, should the deviation condition persist after one tap change.

LDC Type (RX, Z)
Defines the type of line drop compensation used. When correctly configured, the LDC estimates the voltage at the load, such that regulation is treated from the consumer's point of view and not directly considering the transformer's secondary voltage. Traditionally there are two types of LDC:

• RX: estimates the voltage drop given the line's series model, composed of an equivalent resistance and reactance. This requires programming the Ur and Ux parameters. Ignores the Z Compensation parameter.
• Z: simplified method in which only a line drop percentage is supplied. Since this method ignores the power factor (or rather, supposes the line and load are resistive), it has lower precision than the RX option. However, it can be adequate when the line drop is relatively small. Requires programming the Z Compensation parameter. Ignores the Ur and Ux parameters.

Ur (-25 to 25V)
Resistive line drop component, in Volts, adjusted to the MFC-201/R's nominal current (5A).

Ux (-25 to 25V)
Inductive line drop component, in Volts, adjusted to the MFC-201/R's nominal current (5A).

Z Compensation (0 to 15%)
Total line drop, as a percentage of the transformer's secondary voltage, adjusted to the MFC-201/R's nominal current (5A).

Maximum Compensation (0 to 25%)
Limits the transformer's voltage increase due to the LDC.

Voltage/Current Phase Difference (0 to 359°)
Defines the phase difference between the voltage and current waveforms in this MFC-201/R's installation configuration.

Sampling Circuit (Monophase, 3-Phase (Phase-Neutral), 3-Phase (Phase-Phase)
Specifies how the PT is connected. This parameter is required for the proper computation of active, reactive and apparent power values.

U< (undervoltage) (10 to 99%, referred to the nominal voltage)
Voltage value under which the MFC-201/R activates an alarm relay and blocks tap changes.

U> (overvoltage) (101 to 199%)
Voltage value over which the MFC-201/R activates an alarm relay and blocks tap changes.

I> (overcurrent) (10 to 199%, referred to the nominal current)
Current value over which the MFC-201/R activates an alarm relay and blocks tap changes.

All functions accessible through the keyboard are also available at a distance through the RS485 serial links. Therefore, it is possible to remotely:

• Read sampled voltages and currents.
• Read the current configuration.
• Perform a partial or complete reconfiguration.
• Read the line voltage, line current, load voltage, active, reactive and apparent power, power factor and voltage deviation.