In many ways, electric actuators are the holy grail. They are precise, efficient, fast to respond, have low support requirements, can be bought cheaply, can be easily retrofitted into existing environments, and in principal can be configured for absurd output torque. There aren’t a lot of downsides here. We’ve harnessed hydraulic and pneumatic power to move things, but that was always a multi-step procedure. With electronics? Nearly everything is built right into the actuator.
Minimal Install Requirements
Facilities using hydraulics and pneumatics need to provide hoses, valves, pumps, compressors, reservoirs, and more. It’s a lot of hardware just to make something move. That’s a lot of money, maintenance time, and space just to have your fully automated, multi-zone heating system. It’s a lot even if you’re automating a brewery or bakery, where the equipment will ultimately save time and money.
Facilities using electrical actuators however, need only provide power and control signals. In some cases, multi-phase power is required, but that mostly boils down to some extra electrical panels and service wires. Each actuator is pretty much independent and will operate regardless of what the rest of the facility is doing. That’s less hardware to keep track of, fewer failure points, and overall easier maintenance.
In terms of a retrofit in existing facilities, that pretty much means you remove the old actuator, install the new one, and plug it in. In principal, it’ll just plugin and work. It’s hard to go wrong with such a setup.
There’s also some power savings to be realized as well. Consider that hydraulic and pneumatic systems are all about the conversion and transmission of force. You’re going to have an electric motor, expending energy to push a fluid, that then pushes through and even expands tubing, and finally makes something move on the other side. Every step of that is more power in than comes out. The electric motor is going to have it’s own energy losses, then the friction and resistance of the fluid will cause losses, the design of the pump/compressor won’t relay all 5, 10, 100 foot-pounds of force that the motor puts in either, and bit by bit, you pay more for less output.
In an electrical actuator, there’s really just one step: the motor turns. The motor will have it’s own losses from friction, resistance, and magnetic fields, but there’s nothing else really sapping power. You get out more per watt than on competing systems. A motor capable of 50 foot-pounds of output is going to deliver that straight to whatever you’re turning or pushing.
Finally, the nature of electric motors allows us to track the rotor position with minimal additional hardware. When an electrical motor turns, it uses magnetic fields. We can use a Hall Effect Sensor to measure that magnetic field. If we ‘zero’ the actuator so we know it’s closed position, we can count rotor RPM’s with this sensor and some cheap processor chips. If we know how many times the rotor has spun, we can calculate the output drive’s position. This sensing can be tuned up to absurd levels of precision. There are CNC machines with operate below thousandths of an inch accuracy in their cuts and offer single-rpm control while spinning at 10K RPM+.
On hydraulic and pneumatic systems, we can achieve a measure of precision, but it comes at a cost. Additional hardware is needed such as laser measuring tools. Even that, that precision is limited to the actuator’s own response time. If the load changes and the actuator changes position as a result, it needs to respond. For hydraulics, that may not be a rapid response. For electrical systems, it can be built into the motor controls directly and react near imperceptibly. That’s a big deal.
A Range of Capabilities
These traits and others will of course, vary by the particular actuator. Cheaper actuators need not be so precise. If you need a cheap duct actuator, that doesn’t need to be super accurate, you can get it cheap and easy. If you need to know how many thosuandths of a degree your valve has opened, it’s pricey but possible. Modern actuator tech, especially electrical tech, is a whole field of configurable possibilities to meet every need cheaply and efficiently, in terms of cost, space, and performance.