Product positioning and model differences
The XR2002 series voltage regulator is a DC excitation control device designed for brushless generators equipped with permanent magnet generators (PMGs). This series includes two models:
XR2002 (standard type): does not have voltage limited volt/hertz (V/Hz) characteristics, suitable for standard operating conditions with low frequency compensation requirements.
XR2002F (frequency compensation type): Built in voltage limited volt/hertz (VLV/Hz) characteristics, suitable for power generation systems that are sensitive to frequency changes and require automatic voltage drop protection at low frequencies.
The two models are completely identical in appearance, wiring terminals, and installation dimensions, with the only difference being the internal frequency compensation algorithm and corresponding front panel markings.
Key technical specifications and selection points
1. DC output capability
Rated continuous output: 7 Adc @ 63 Vdc (corresponding to 440W)
Strong excitation output (1 minute): 10 Adc @ 90 Vdc (corresponding to 900W)
The output capability determines the adaptation range of the magnetic field resistance of the exciter. The manual specifies that the DC resistance of the excitation winding must be between 9 Ω and 100 Ω. If the resistance is lower than 9 Ω, a current limiting resistor must be connected in series; If the full load current exceeds 7A, a higher output level regulator needs to be selected.
2. Input power conditions
The regulator can be powered by PMG or generator terminal voltage, with different wiring methods and voltage ranges:
Power supply source phase number voltage range (full load → no load) frequency range
PMG single-phase 100-180 Vac 48-480 Hz
PMG three-phase 70-140 Vac 48-480 Hz
Generator output (isolated transformer) single-phase 90-153 Vac 48-480 Hz
Generator output (isolated transformer) three-phase 70-110 Vac 48-480 Hz
3. Voltage sensing input
The detection input is single-phase, with terminals E1 (multi tap) and E3 (common terminal). Select the corresponding E1 tap based on the rated voltage of the generator:
100-139 Vac → 120V tap
190-240 Vac → 208/240V tap
380-480 Vac → 416/480V tap
500-600 Vac → 600V tap
Important engineering reminder: Phase to phase wiring must be used for input detection, and phase to neutral wiring is prohibited, otherwise the third harmonic will seriously affect the adjustment accuracy.
Deep Analysis of Frequency Compensation Mechanism (XR2002F Only)
XR2002F provides two frequency compensation modes to address the voltage control requirements of the generator during sudden load surges or speed fluctuations.
1. Voltage/Hertz (V/Hz) characteristics
This mode is a linear relationship: when the frequency decreases, the voltage decreases proportionally to maintain a constant V/Hz ratio. This feature is mainly used to improve the system recovery performance under sudden load conditions - the voltage will not excessively rise before frequency recovery. The UF ADJ control and VOLT control on the front panel work together to adjust the characteristic curve simultaneously along the frequency axis (45-65Hz) and voltage axis. The preset inflection point at the factory is 55Hz (60Hz system).
2. Voltage limited volt/hertz (VLV/Hz) characteristics
This mode adds a linear regulation zone based on the V/Hz characteristic, which means that the regulator can still maintain precise voltage regulation even when the frequency fluctuates slightly; The voltage only decreases proportionally when the frequency drops below the inflection point. This allows the generator to maintain voltage stability even with slight speed fluctuations, balancing dynamic response and steady-state accuracy.
The inflection points of both characteristics can be adjusted through the UF ADJ knob, and the corresponding frequency range for 50Hz and 60Hz systems needs to be selected through internal jumpers.

Key points of installation and wiring engineering
1. Installation and heat dissipation
It is recommended to install the regulator vertically to facilitate convective heat dissipation. Its structure is sturdy and can be directly installed on the generator set, but the correct fasteners need to be used. Please refer to the Outline Drawing in the manual for detailed dimensions.
2. Excitation output circuit (F+, F -)
It is necessary to strictly observe the polarity connection to the magnetic field terminals of the brushless excitation machine.
It is absolutely forbidden to string the shutdown switch into the F+and F - circuits. Due to the possibility of arc damage to the regulator, the shutdown switch must be connected between terminal 53 and F+(there is already a jumper at the factory, which can be replaced with a switch).
3. Power input fuse configuration
It is strongly recommended to install high breaking capacity fuses in each input power line to protect the regulator from external short circuits or ground faults.
4. Excitation circuit (applicable only when the generator outputs power)
When the regulator is powered by the generator terminal voltage, if it is first put into operation or the residual magnetic polarity is incorrect, it needs to be excited through an external DC power supply (Field Flashing). The wiring method is: DC power supply positive pole → diode → current limiting resistor → F+, negative pole → F -. The starting excitation current should be set between 1/2 of the rated no-load excitation current and the full load value, and the calculation formula is: