1. Introducció
The Walfront STVP-936 series automatic reset over-voltage, baix voltage, and multi-function protector is a sophisticated monitoring and auxiliary device designed for three-phase four-wire power systems and electrical equipment. This device provides comprehensive protection by instantly cutting off the power supply to prevent damage to electrical equipment when conditions such as overvoltage, minvartage, or overcurrent occur. Once the line voltage returns to normal, the protector automatically restores the power supply.
This protector integrates multiple functions including over-voltage, baix voltage, over-current, three-phase current (voltage) unbalance, phase sequence (phase dislocation), and phase-break detection. It also features fault inquiry, voltmeter and ammeter functions, and the ability to restore factory settings. The clear LCD screen provides easy access to all functions and settings.
2. Informació de seguretat
ADVERTIMENT: Installation and maintenance should only be performed by qualified electricians in accordance with local electrical codes and regulations. Failure to follow these instructions may result in electric shock, fire, or serious injury.
- Ensure power is disconnected before installation or any maintenance.
- Verify correct wiring connections for three-phase four-wire systems.
- No feu funcionar el dispositiu si sembla que està danyat.
- Mantingueu el dispositiu allunyat de la humitat i de les temperatures extremes.
- The device is designed for indoor use within specified environmental conditions.
3. Producte acabatview

Figura 3.1: Frontal view of the Walfront STVP-936 Voltage Protector, showing the LCD display and control buttons.
The STVP-936 is a compact device designed for DIN rail mounting. It features an LCD display for real-time voltage and current readings, as well as for navigating settings. Control buttons allow for adjustment of protection parameters.
Característiques principals:
- Automatic reset function after fault clearance.
- Integrated protection against over-voltage, baix voltage, sobreintensitat.
- Three-phase current (voltage) unbalance protection.
- Phase sequence (phase dislocation) and phase-break protection.
- Fault inquiry function.
- Built-in voltmeter and ammeter.
- Factory settings restoration option.
- Clear LCD display for easy monitoring and configuration.
4. Especificacions

Figure 4.1: Dimensions of the Walfront STVP-936 Voltage Protector.
| Paràmetre | Valor |
|---|---|
| Tipus d'element | Ajustable Voltage Protector |
| Material | Plàstic |
| Model | STVP-936 |
| Voltage (Three-Phase Four-Wire) | 230V/400VAC 50/60Hz |
| Valoració actual | 1-50A adjustable (default 50A) |
| OvervoltagRang de valors electrònics | 221V-300V-OFF (default 280V) |
| Overvoltage Recovery Value Range | 220V- (default 250V) |
| Overvoltage Action Time | 0.1 - 10 seconds (default 0.2 seconds) |
| UndervoltagRang de valors electrònics | 219V-150V-OFF (default 160V) |
| Undervoltage Recovery Value Range | 220V-151V (default 180V) |
| Undervoltage Action Time | 0.1 - 10 seconds (default 0.2 seconds) |
| Overcurrent Action Time | 1 - 512 seconds (default 5 seconds) |
| Trifàsic Voltage Unbalance Value Range | 5%-90%-OFF (default 25%) |
| Fase Voltage Unbalance Action Time | 0.1 - 10 seconds (default 2.0 seconds) |
| Power-On Delay Time | 2 - 255 seconds (default 2 seconds) |
| Failure Recovery Delay Time | 2 - 512 seconds (default 60 seconds) |
| Consum d'energia | ≤ 3VA |
| Mode de visualització | LCD |
| Electrical Isolation Strength | >2000VAC, pulse 2.5KV 1.2/50μS |
| Temperatura de l'entorn de treball | -20 ℃ ~ 50 ℃ |
| Ambient de treball Humitat | <85% |
| Working Environment Altitude | No més de 2000 metres |
| Dimensions aproximades (L x A x A) | 70 x 95 x 65 mm (2.8 x 3.7 x 2.6 polzades) |
| Pes de l'article | 13.5 unces |
5. Configuració i instal·lació
The Walfront STVP-936 is designed for DIN rail mounting within an electrical enclosure. Ensure the enclosure provides adequate ventilation and protection from environmental factors.

Figura 5.1: Frontal view showing the 'IN' (input) and 'OUT' (output) terminals for wiring.
Instruccions de cablejat:
- Desconnexió d'alimentació: Before beginning any wiring, ensure that the main power supply to the circuit is completely disconnected and locked out to prevent accidental re-energization.
- Muntatge: Mount the STVP-936 onto a standard DIN rail securely.
- Input Wiring (IN terminals):
- Connect the incoming three-phase power lines (L1, L2, L3) and the Neutral line (N) to the corresponding 'IN' terminals at the top of the device.
- Assegureu-vos que totes les connexions estiguin ben ajustades i segures per evitar contactes solts i sobreescalfament.
- Output Wiring (OUT terminals):
- Connect the protected load's three-phase power lines (L1, L2, L3) and the Neutral line (N) to the corresponding 'OUT' terminals at the bottom of the device.
- Verify that the load's current requirements do not exceed the device's maximum current rating (50A for this model).
- Posada a terra: Ensure proper grounding of the electrical system as per local codes.
- Verificació: Double-check all wiring connections for correctness and tightness before restoring power.

Figura 5.2: De dalt a baix view illustrating the terminal block layout for wiring connections.
6. Instruccions de funcionament
After successful installation and power-up, the device's LCD will display real-time voltage and current readings. The device is pre-configured with default settings, but these can be adjusted to suit specific application requirements.

Figure 6.1: Close-up of the LCD display and control buttons (SET, Up, Down).
Pantalla i controls:
- Pantalla LCD: Mostra el volum en temps realtage (V), current (A), and various protection parameters during configuration.
- Botó SET: Used to enter the setting mode and confirm parameter changes.
- Botons amunt / avall: Used to navigate through settings and adjust parameter values.
Paràmetres d'ajust:
- Manteniu premut el botó SET button for a few seconds to enter the parameter setting mode.
- Utilitza el Up i Avall buttons to scroll through the different adjustable parameters (e.g., Overvoltage Value, Undervoltage Value, Overcurrent Action Time, etc.).
- When the desired parameter is displayed, press the SET button briefly to select it for adjustment.
- Utilitza el Up i Avall buttons to change the value of the selected parameter.
- Premeu el botó SET button again to confirm the new value and move to the next parameter, or to exit the setting mode if no further changes are needed.
- If no buttons are pressed for a certain period, the device may automatically exit the setting mode and save changes.
Refer to the Specifications section (Section 4) for the default values and adjustable ranges of each parameter.
Fault Inquiry and Reset:
- The device automatically detects faults and disconnects power. The LCD will typically display the type of fault.
- After a fault condition clears and the recovery delay time (default 60 seconds) has passed, the device will automatically reset and restore power.
- To inquire about past faults, consult the device's specific menu options using the SET and Up/Down buttons.
- To restore factory settings, there is usually a specific sequence or menu option. Refer to the on-screen prompts or a more detailed manufacturer's guide if available.
7. Manteniment
The Walfront STVP-936 Voltage Protector is designed for minimal maintenance. However, regular checks can ensure optimal performance and longevity.
- Inspecció visual: Inspeccioneu periòdicament el dispositiu per detectar qualsevol signe de danys físics, decoloració o connexions soltes.
- Neteja: Keep the device clean and free from dust. Use a dry, soft cloth for cleaning. Do not use liquid cleaners or solvents.
- Comprovacions de connexió: Ensure all wiring connections remain tight and secure. Loose connections can lead to overheating and device malfunction.
- Condicions ambientals: Verifiqueu que l'entorn operatiu es mantingui dins dels rangs de temperatura i humitat especificats.
- Prova de funcionalitat: If possible and safe to do so, periodically test the protection functions by simulating a fault condition (e.g., temporarily reducing voltage if a test setup is available) to ensure the device responds correctly. This should only be done by qualified personnel.
No intenteu obrir ni reparar el dispositiu vosaltres mateixos. Encarregueu totes les tasques de manteniment a personal qualificat.
8. Solució De Problemes
This section provides guidance for common issues. For problems not listed here, contact technical support.
| Problema | Causa possible | Solució |
|---|---|---|
| El dispositiu no s'encén. | No hi ha alimentació d'entrada; cablejat incorrecte; error intern. | Check main power supply. Verify input wiring (L1, L2, L3, N). If power is present and wiring is correct, the device may be faulty. |
| El dispositiu s'encén amb freqüència. | Voltage fluctuations (over/under); overcurrent condition; phase unbalance; incorrect settings. | Monitor line voltage and current. Check load for overcurrent. Verify protection parameter settings (overvoltage, minvartage, overcurrent, unbalance thresholds). Adjust settings if necessary, ensuring they are appropriate for your system. |
| Device does not reset after fault clears. | Fault condition still present; recovery delay time not elapsed; internal fault. | Ensure the fault condition (e.g., overvoltage) has genuinely cleared. Wait for the configured failure recovery delay time to elapse. If the issue persists, power cycle the device (if safe) or contact support. |
| La pantalla LCD està en blanc o és erràtica. | No power; display fault; internal malfunction. | Check power supply. If power is present, try power cycling the device. If the problem persists, the device may require servicing. |
| No es poden ajustar els paràmetres. | Incorrect button sequence; device locked. | Ensure you are pressing and holding the SET button correctly to enter setting mode. Follow the operating instructions precisely. |
9. Garantia i Suport
Specific warranty information for the Walfront STVP-936 Voltage Protector is not provided in this manual. Please refer to the product packaging, your purchase documentation, or contact your retailer or Walfront customer service for details regarding warranty coverage and terms.
For technical support, troubleshooting assistance beyond this manual, or inquiries about replacement parts, please contact Walfront customer support through their official weblloc web o la informació de contacte proporcionada amb la compra.





