A30-U3 DC Voltage Relay Instruction Manual

1. Product Overview

The A30-U3 is a versatile DC voltage controller featuring digital display for real-time voltage detection and relay control. It allows for adjustable upper and lower voltage limits (0-99.9V) and can trigger relay actions based on voltage exceeding or falling below these limits. The device also supports adjustable delay times for relay activation and deactivation. It is designed for applications such as voltage detection switches, battery overvoltage and undervoltage protection, charge and discharge control, and voltage alarm systems. This version offers a higher working power supply range and increased relay load capacity compared to previous models.

Figure 1: A30-U3 DC Voltage Relay with highlighted features including 6-80V working power, 30A relay output, adjustable sensitivity, and delay.

2. Safety Precautions

• Voltage Limit: Do not use with solar panels producing output voltage above 80V. Even with MPPT or PWM charge controllers, pulse voltages exceeding 80V can damage the product.
• Battery Compatibility: Not suitable for 72V batteries that can fully charge to 85V.
• Charger Connection: For DC48V and above batteries, PWM or MPPT solar chargers may generate pulse voltages above 80V. Do not directly connect the charger to supply power to this product without proper isolation.
• Relay Load: When connecting to a DC load with voltage above 30V, the on-load current capacity of the relay will be reduced (e.g., maximum 10A at 60V DC). Exceeding the specified load range will affect the service life of the relay.
• Wiring: Ensure all wiring is correct and secure before applying power. Incorrect wiring can lead to damage or malfunction.

3. Setup and Wiring

3.1 Terminal Connections

The A30-U3 controller features several terminals for power, voltage detection, and relay output:

• Power Supply: Connect DC 6-80V to the "Power+" and "GND" terminals.
• Voltage Detection Input: Connect the positive voltage to be detected to "Volt+" and the negative to "GND". Important: The negative electrode of the voltage detection input and the negative electrode of the power supply are jointly connected.
• Relay Output: The relay has three contacts for load control:
  • COM: Common point
  • NC: Normally Closed (connected to COM when relay is released/unpowered)
  • NO: Normally Open (connected to COM when relay is pulled-in/powered)
  The relay contact acts as a switch. Wire the load in series within the power circuit. Do not short-circuit the power supply through the relay contacts.

Figure 2: Comprehensive wiring diagrams for various applications. Top: Control of 220V AC charger input. Middle: Switching between primary and secondary batteries for charging. Bottom: Battery discharge low voltage protection. Also shows detailed component layout and terminal labels.

3.2 Example Wiring: Battery Low Voltage Protection

For battery discharge low voltage protection, connect the battery to the "Power+" and "GND" terminals for power supply to the controller. Connect the positive terminal of the battery to "Volt+" for voltage detection. The load should be connected in series with the "COM" and "NC" (Normally Closed) terminals of the relay if you want the load to be connected when the voltage is normal and disconnected when it drops below the set threshold. Alternatively, use "COM" and "NO" (Normally Open) if you want the load to be connected when the voltage drops below the threshold (e.g., for an alarm).

3.3 Example Wiring: Charger Control

To control a 220V AC charger, the controller's relay output (COM and NC/NO) can be wired in series with the 220V AC input to the charger. The controller's power and voltage detection inputs should be connected to the battery being charged. This allows the controller to monitor battery voltage and activate/deactivate the charger as needed.

4. Operating Instructions

The A30-U3 controller offers four main operating modes (P-1, P-2, P-3, P-4) and a setting procedure using the "SET" and "ENTER" buttons.

4.1 Setting Procedure

Use the "SET" button to cycle through different parameters and the "ENTER" button to adjust values (0-9 cycle). The general setting flow is as follows:

Figure 3: Setting flow for the A30-U3 controller. Parameters include Upper Limit Value, Lower Limit Value, Voltage Correction, Detection Sensitivity (d-6), and End Settings (ON H/L).

1. Press SET to enter setting mode.
2. Adjust Upper limit value (00.0) using ENTER.
3. Press SET. Adjust Lower limit value (00.0) using ENTER.
4. Press SET. Adjust Voltage correction (00.0) using ENTER.
5. Press SET. Adjust Detection sensitivity (d-6) using ENTER.
6. Press SET. Select End Settings (ON H or ON L) using ENTER.
7. Press SET again to save and exit.

4.2 Operating Modes

The A30-U3 supports four working modes, configurable for various control scenarios:

• P-1 Delay Setting:

  This mode allows setting the relay release delay time (T1) and suction (pull-in) time (T2), both adjustable from 0-999 seconds. A digital tube display shutdown delay (0-9 minutes) can also be configured. If T1 is 005 and T2 is 000, the relay delays 5 seconds before releasing and then remains pulled in. If T1 is 000 and T2 is 005, the relay pulls in immediately and releases after 5 seconds. If T1 is 005 and T2 is 006, the relay delays 5 seconds before pulling in, and then releases after 6 seconds. Factory default for T1 and T2 is 0, meaning direct voltage control without delay.
• P-2 Voltage Detection Control (Initial Release):

  In this mode, the system continuously monitors the DC voltage. The relay is initially released. If the detected voltage exceeds the set upper limit, the relay releases. If it falls below the lower limit, the relay pulls in (or vice-versa, depending on "ON H" or "ON L" setting). Any delays set in P-1 mode will apply. For example, if T1 is 003 in P-1 and "ON H" is set in P-2, the relay will delay 3 seconds before pulling in when the voltage exceeds the upper limit.

• P-3 Voltage Detection Control (Initial Pull-on):

  Similar to P-2, but the relay is initially pulled-on. This mode is primarily used for delay disconnect functions. For instance, if T1 is 000 and T2 is 003 in P-1, and "ON L" is set in P-3, the relay will delay 3 seconds before releasing when the detected voltage drops below the lower limit.

• P-4 Overvoltage and Undervoltage Control (Voltage Range Action):

  This mode allows the relay to act when the detection voltage is within the upper and lower limits, or outside them. Unlike P-2 and P-3, P-4 mode has a fixed return difference of 0.2V to prevent rapid switching due to minor voltage fluctuations. If "ON H" is set, the relay pulls in when the voltage is within the limits. If "ON L" is set, the relay releases when the voltage is within the limits. Delays set in P-1 apply. For example, if T1 is 003 and T2 is 000 in P-1, and "ON L" is set in P-4, the relay will delay 3 seconds before switching from release to pull-in when the detection voltage exceeds the upper or lower limits.

5. Specifications

6. Maintenance

The A30-U3 controller is designed for durability and requires minimal maintenance. Key aspects include:

• Parameter Retention: All set parameters are stored in non-volatile memory and will be retained even after power loss for up to 30 years.
• Environmental Conditions: Ensure the device operates within the specified working environment temperature of -40℃ to +85℃ to maintain optimal performance and longevity.
• Physical Inspection: Periodically inspect wiring connections for tightness and signs of wear or corrosion.
• Cleaning: Keep the device free from dust and debris. Use a soft, dry cloth for cleaning. Do not use liquid cleaners.

7. Troubleshooting

• Device Not Powering On:
  • Verify that the power supply is within the DC 6-80V range and correctly connected to "Power+" and "GND".
  • Check for any loose connections or damaged wires.
• Relay Not Activating/Deactivating as Expected:
  • Confirm that the voltage detection input ("Volt+" and "GND") is correctly wired and receiving the expected voltage.
  • Review the set upper and lower voltage limits in the operating mode (P-2, P-3, P-4) to ensure they match your desired control logic.
  • Check P-1 delay settings (T1, T2). If delays are set, the relay action will not be instantaneous.
  • Ensure the "ON H" or "ON L" setting in P-2, P-3, or P-4 mode is configured correctly for your application.
• Inaccurate Voltage Reading:
  • Check the voltage correction setting (00.0 in the setting procedure) and adjust if necessary to calibrate the reading against a known accurate voltmeter.
  • Ensure stable power supply and detection voltage.
• Relay Overload:
  • If the relay is frequently failing or showing signs of damage, ensure the connected load's current and voltage do not exceed the relay's maximum contact load specifications, especially for DC loads above 30V.

8. User Tips

• Common Ground: Always remember that the negative terminal for voltage detection ("GND") must be common with the negative terminal of the power supply.
• Solar Panel Caution: When using with solar charging systems, be extremely cautious about voltage spikes. If your solar panel or charger can produce voltages above 80V, even momentarily, this product is not suitable.
• Control Within a Range: If you need the relay to activate when the voltage is within a specific upper and lower limit, utilize the P-4 operating mode. This mode is specifically designed for bidirectional action based on voltage range.
• Delay Customization: Leverage the P-1 delay settings (T1 and T2) to fine-tune the response time of the relay, preventing rapid cycling or providing a necessary buffer before action.
• Load Matching: Pay close attention to the relay's contact load ratings. For DC loads, especially those above 30V, the maximum current capacity decreases. Ensure your load is well within these limits to prolong the relay's lifespan.

9. Warranty and Support

For warranty information or technical support, please refer to the seller's policies or contact the point of purchase. Keep your purchase receipt for any warranty claims.