SLA-12V 30A High Power Relay Module

The SLA-12V 30A High Power Relay Module is a single-channel electromagnetic relay board designed to control AC or DC electrical loads using a low-power control signal. The module is equipped with an SLA-12VDC-SL-A high-power relay featuring a 12 V DC coil and a normally open switching contact.

It can be controlled by microcontrollers, automation controllers, sensors, thermostats, timers, alarm systems and other electronic control devices. Optocoupler isolation helps reduce interference transferred between the control electronics and the relay-driving circuit.

Important: the 30 A marking represents the maximum contact rating of the relay itself. The permissible continuous current of the complete module also depends on the screw terminals, PCB tracks, wire cross-section, cooling conditions and load type. For high continuous currents or demanding inductive loads, the module should be used to control an external power contactor.

Main features

• One independent relay channel
• 12 V DC module and relay-coil supply
• High-power SLA-series electromagnetic relay
• Normally open relay output – NO
• Electrical separation between the control and load circuits
• Optocoupler-isolated control input
• High-level or low-level triggering, depending on the module version and jumper setting
• Relay-status LED indicator
• Screw terminals for power and load connections
• Suitable for switching AC and DC loads
• Compact printed circuit board design
• Suitable for installation inside automation equipment or a protective enclosure

Technical specifications

Parameter	Value
Product type	Single-channel electromagnetic relay module
Module supply voltage	12 V DC
Relay model	SLA-12VDC-SL-A
Rated coil voltage	12 V DC
Coil type	Non-polarized, non-latching
Coil power consumption	Approximately 0.9 W
Coil resistance	Approximately 160 Ω
Contact configuration	SPST-NO / 1 Form A
Contact state without power	Normally open
Maximum relay contact current	Up to 30 A, depending on the load and operating conditions
Maximum switched AC voltage	Up to 250 V AC
Typical DC load voltage	Up to 30 V DC
Maximum relay switching capacity	Up to 7200 VA according to the relay specification
Contact resistance	Up to 100 mΩ
Relay operate time	Up to 10 ms
Relay release time	Up to 10 ms
Insulation resistance	At least 100 MΩ at 500 V DC
Dielectric strength between coil and contacts	2000 or 4000 V AC, depending on the relay version
Dielectric strength between open contacts	1000 V AC
Operating temperature	Approximately –40 °C to +85 °C
Permissible relative humidity	45–85% RH at 20 °C
Trigger type	High-level or low-level triggering, depending on the version
High-level input voltage	Up to 12 V DC
Control input current	Up to approximately 100 mA, depending on the module version
Control-circuit isolation	Optocoupler
Load connection	Screw terminals
Status indication	Relay-status LED
Relay body dimensions	Approximately 32 × 27.6 × 25.5 mm
Relay weight	Approximately 23 g
Installation	Installed inside equipment or a suitable protective enclosure

Contact operation

The module uses a normally open relay contact:

• COM – common contact;
• NO – normally open contact.

When no trigger signal is applied, COM and NO remain disconnected. When the relay is activated, COM and NO are electrically connected.

Because the module uses an SLA-12VDC-SL-A relay, it normally does not provide an NC load terminal.

Operating principle

1. A 12 V DC supply is connected to the module.
2. A suitable logic signal is applied to the control input.
3. The optocoupler and transistor driver energize the relay coil.
4. The COM and NO contacts close.
5. When the trigger signal is removed, the relay releases and the contacts open.

Some versions include a jumper for selecting high-level or low-level triggering. Always check the markings printed on the actual PCB, such as VCC, GND, IN, H/L, COM and NO.

Typical applications

• Lighting control
• Electric heater control
• Fan and pump control
• Solenoid valve control
• Automatic irrigation systems
• Automotive and 12 V electrical systems
• Home and industrial automation
• Security and alarm systems
• Increasing the switching capability of thermostats and timers
• Microcontroller projects
• Arduino, ESP32, STM32, PLC and other controller projects
• External contactor and power-relay control

Load considerations

The permissible switching current depends strongly on the load type:

• Resistive loads: heaters, incandescent lamps and other loads without a large starting current.
• Inductive loads: motors, transformers, pumps, fans, solenoid valves and contactor coils.
• Capacitive loads: LED power supplies, switch-mode power supplies and circuits containing large capacitors.

Inductive, capacitive and LED loads may draw an inrush current several times higher than their nominal current. The relay operating current must therefore be reduced for these applications.

Installation recommendations

• Power the module from a stable 12 V DC supply.
• Observe the correct VCC and GND polarity.
• Select the load-wire cross-section according to the actual current.
• Use short, adequately sized cables in high-current circuits.
• Install a correctly rated fuse or circuit breaker in the load circuit.
• Do not exceed the current rating of the terminals, PCB tracks or connecting wires.
• Use a flyback diode when switching a DC inductive load.
• Use an RC snubber or varistor when switching an AC inductive load.
• Do not install the module where moisture, condensation or conductive dust may accumulate.
• When switching 230 V AC, install the module inside a closed, insulated and flame-resistant enclosure.
• Mains-voltage wiring must be carried out by a qualified person.

Package contents

• 1 × SLA-12V 30A single-channel high-power relay module

Note

The appearance, terminal markings, trigger-selection method and installed components may vary between production batches. Check the markings and wiring diagram of the supplied module before installation.