How to Use G3MB-202P: Examples, Pinouts, and Specs

The G3MB-202P is a compact and reliable solid-state relay (SSR) designed for controlling high voltage and current loads using a low voltage control signal. It features an opto-isolated input for enhanced safety and electrical isolation, making it ideal for applications where electrical noise or interference is a concern. The G3MB-202P can switch AC loads up to 2A at 240VAC, making it suitable for a wide range of automation and control systems.

• Home automation systems (e.g., controlling lights, fans, or appliances)
• Industrial control systems
• Microcontroller-based projects (e.g., Arduino, Raspberry Pi)
• HVAC systems
• Motor control and switching
• Noise-sensitive environments requiring electrical isolation

Below are the key technical details of the G3MB-202P solid-state relay:

The G3MB-202P has four pins, as described in the table below:

1. Connect the Control Signal:

   • Connect the positive control signal (e.g., from a microcontroller like Arduino) to the Input (+) pin.
   • Connect the ground of the control signal to the Input (-) pin.

2. Connect the AC Load:

   • Connect one terminal of the AC load to the Output (AC1) pin.
   • Connect the other terminal of the AC load to the Output (AC2) pin.

3. Power the Control Circuit:

   • Ensure the control signal voltage is within the specified range (5V DC).

4. Switching the Load:

   • When the control signal is applied, the relay will switch the AC load on or off.

• Electrical Isolation: The opto-isolated input ensures safety, but always double-check connections to avoid short circuits.
• Load Ratings: Do not exceed the maximum output current of 2A or the voltage range of 75VAC to 264VAC.
• Heat Dissipation: Ensure proper ventilation or heat sinking if the relay is used near its maximum current rating.
• Zero-Cross Switching: The relay uses zero-cross switching to minimize electrical noise and prolong the life of the load.

Below is an example of how to control an AC load using the G3MB-202P and an Arduino UNO:

// Example: Controlling an AC load with G3MB-202P and Arduino UNO

const int relayPin = 7; // Pin connected to the G3MB-202P Input (+)

void setup() {
  pinMode(relayPin, OUTPUT); // Set the relay pin as an output
  digitalWrite(relayPin, LOW); // Ensure the relay is off at startup
}

void loop() {
  digitalWrite(relayPin, HIGH); // Turn the relay on (AC load ON)
  delay(5000); // Keep the load on for 5 seconds
  digitalWrite(relayPin, LOW); // Turn the relay off (AC load OFF)
  delay(5000); // Keep the load off for 5 seconds
}

Note: Always ensure proper safety precautions when working with high voltage AC loads. Disconnect power before making any changes to the circuit.

1. The relay does not switch the load:

   • Verify that the control signal voltage is within the specified range (5V DC).
   • Check the wiring of the control signal and AC load.
   • Ensure the AC load is within the relay's rated voltage and current.

2. The relay gets too hot:

   • Ensure the load current does not exceed 2A.
   • Provide adequate ventilation or use a heat sink if necessary.

3. Electrical noise or interference:

   • Use proper grounding and shielding techniques in your circuit.
   • Ensure the relay is not placed near high-frequency noise sources.

4. The relay switches erratically:

   • Check for stable and noise-free control signals.
   • Verify that the power supply to the control circuit is sufficient.

Q: Can the G3MB-202P be used with a 3.3V control signal?
A: No, the G3MB-202P requires a 5V DC control signal for proper operation.

Q: Is the relay suitable for DC loads?
A: No, the G3MB-202P is designed for AC loads only and cannot switch DC loads.

Q: Can I use the relay to control inductive loads like motors?
A: Yes, but ensure the load is within the relay's rated current and voltage. For inductive loads, consider using a snubber circuit to protect the relay.

Q: Does the relay provide electrical isolation?
A: Yes, the opto-isolated input provides electrical isolation between the control and load circuits.