Relay 1RT 30A Grove

Quick Answer: The Relay 1RT 30A Grove is a Grove module carrying an electromechanical relay with a single changeover contact, listed with a 30 A contact rating. A low-power signal from a microcontroller energises the relay coil, and the contacts switch a separate circuit that the board could not drive directly.

What 1RT and 30A Mean

1RT is the French shorthand for one changeover contact, known in English as single-pole double-throw, or SPDT. The relay has a common terminal, a normally closed terminal joined to common while the coil is off, and a normally open terminal joined when the coil is energised. The 30 A in the listing title describes the relay contacts; the safe current for a whole project also depends on the terminals, board tracks and cables, so check the module documentation before relying on that figure.

Relays teach an important idea: electrical isolation. The coil circuit and the contact circuit are separate, so a 3.3 V or 5 V control signal can switch a lamp, pump or fan running from its own supply. Students hear the click as the armature moves, can confirm the change with a multimeter on continuity mode, and learn why a driver transistor and flyback diode are needed, parts that Grove relay boards usually carry on the module.

In schools the relay should switch only low-voltage loads such as a 12 V fan, pump or lamp from a bench supply or battery. Mains wiring is not a student activity and should only be done by a qualified person, with the module enclosed.

Specifications

Safe Use

• Keep switched circuits at safe low voltages in the classroom and never let students connect mains supplies.
• Switch off the load supply before changing wires on the screw terminals, and tighten the terminals firmly.
• Inductive loads such as motors spark at the contacts; a suppression component across the load reduces contact wear.
• Do not touch the underside of the board while a load circuit is powered.

Applications

• Switching a 12 V fan from a temperature reading in a thermostat model
• Turning a small pump on and off in a plant-watering project
• Automatic lighting model controlled by a light sensor or timer
• Showing NO and NC contacts with two low-voltage lamps

Why Choose LabEquip

Relay modules are typically bought by schools teaching control systems and automation, where students move from lighting an LED to switching a real load. LabEquip lists the relay in its STEM kits range, and pairing it with the Grove temperature sensor gives a complete thermostat exercise. For quantities, use the contact page.

Frequently Asked Questions

What do NO, NC and COM mean on the relay?

COM is the common terminal. NC, normally closed, is connected to COM when the relay is off. NO, normally open, is connected to COM when the relay is on. Wire the load through COM and NO if it should run only when the program switches the relay on.

Can students use the relay to switch mains appliances?

No. In schools the relay should only switch low-voltage circuits such as battery or bench-supply loads. Mains voltages can cause fatal shocks, and any mains installation must be carried out by a qualified electrician in a proper enclosure.

Why does a microcontroller need a relay at all?

A microcontroller pin supplies only a very small current at a low voltage. A relay lets that small signal control a separate circuit with its own supply, keeping the board electrically isolated from the load and safe from damage.

What does the 30 A rating mean for my project?

It is the contact rating given in the listing title. The safe current for a real circuit also depends on the terminals, board tracks, cable size and load type. Classroom projects stay far below it, typically a fraction of an ampere to a few amperes at low voltage.

Why does the relay click?

The coil becomes an electromagnet when energised and pulls a metal armature, which moves the contacts. The click is that movement, and it is a useful audible check that the program has switched the relay.

How is a relay different from a transistor or MOSFET switch?

A relay uses moving contacts, isolates the two circuits completely and can switch AC or DC. A transistor or MOSFET switches silently and faster with no wear, but usually only DC and without isolation. Relays suit slow on-off control.

Last Updated: September 2026