Homes are getting smaller. Kitchen space in turn is being minimized. Appliances are following this trend; they have become more space- and energy-efficient. Along with all the IoT functionality being built into the standard microwave, refrigerator, or coffee maker, the newest appliances can have more advanced control systems, electronic hardware, display systems, and connectivity (to a smartphone).These trends are forcing electronic component manufacturers to downsize the footprint of the components that are utilized in OEM end-products. The benefits of smaller components is bigger than overall size: they need to operate faster and consume less energy on top of the reduced footprint. Omron's G6QE Power Relay is an example of a miniature PCB-mounted power relay that can be used in home appliances, industrial machinery, building automation, PLCs, temperature controllers, air conditioning compressors, and power supplies.
G6QE PCB Power Relays by Omron are low-height (20.5 mm) single-pole, power relays with a high-switching current capability of 36 A @250 VAC and 10,000 operations or 30 A @250 VAC and 100,000 operations in a miniature package. It has a 10kV impulse withstand voltage (between coil and contacts). Power consumption is reduced to 12% compared to rated coil consumption by lowering the applied voltage to the coil after applying nominal voltage for 100 ms relay operation. The G6QE conforms to cULus, EN and CQC standards. The G6QE allows engineers to design smaller-sized products yet not sacrificing high-current switching capacity.
A simple application circuit using an SPST Relay is shown on the left. A power source is connected to the relay coil through a switch. The output contact is connected a lamp load and an AC power source. When the switch is turned ON, the relay coil is energized, making output contact to close, which results in current flow through lamp. When the switch is turned OFF, the relay coil is de-energized, and contact is opened.
The G6QE is a single-side, stable relay where the contact is opened or closed only while an input signal is received. When the input signal is removed, the contact reverts to the previous state. Switching capacity is rated with both voltage and current. Load voltage is the voltage across the terminals of the relay in its open condition. The load current is the current that flows through both the load and relay in a closed condition. The maximum current that can be switched with contacts is for resistive loads. A relay rated double the operating current should be selected for inductive loads generating inrush or surge currents. (Note: the G6QE is not designed to switch microloads of less than 100mA, e.g., signal applications.)
One of the primary benefits of the G6QE relay is its low power consumption. Power consumption of the relay can be reduced if the the coil voltage is reduced to the holding voltage after relay operates. The relay operates by applying rated voltage to the coil for at least 100 ms. A voltage of at least 35% of the rated voltage is required to hold the coil.
Mounting Guidelines for PCB Relays
PCBs are classified into those made of epoxy and those made of phenol. The following table lists the characteristics of these PCBs. Epoxy PCBs are recommended for mounting Relays to prevent the solder from cracking.
The PCB may warp due to size, mounting method, or ambient operating temperature of the PCB or the weight of components mounted to the PCB. Should warping occur, the internal mechanism. of the relay on the PCB will be deformed and the Relay may not
provide its full capability. Determine the thickness of the PCB by taking the material of the PCB into consideration. In general, PCB thickness should be 0.8, 1.2, 1.6, or 2.0 mm. Taking Relay terminal length into consideration, the optimum thickness is 1.6 mm.
While deciding the thickness of the PCB, the PCB material and relay terminal length should be taken into consideration. Use the relay specifications to decide on the terminal hole and land diameters, based on the relay mounting dimensions. When mounting a relay, check for the specified amount of mounting space. When two or more relays are mounted, their interaction may generate excessive heat. In addition, if multiple PCBs with relays are mounted to a rack, the temperature may rise excessively. Leave enough space so that heat will not build up. When two or more relays are mounted, relay characteristics may be changed by interference from the magnetic fields generated by the individual relays. Be sure to conduct tests using the actual devices.
Examples of PCB Power Relays