Analog or Digital?
“Generator control unit” is an ambiguous term that could mean a variety of things to an owner or operator of a mobile generator. It could be as narrowly defined as the operator interface panel — the switches, controls and connections — used to run the generator. It could be more broadly defined as a combination of every electrical part or computer system of the generator unit and its engine. When the “generator control unit” or “control panel” is referenced in this feature, it will be to describe the interface of the generator that the operator is concerned about and interacts with.
The main concern with any generator control unit, from a manufacturer standpoint, is providing the operator with the essential information he or she needs to know regarding how the machine is performing and how the machine is being controlled. The challenge in designing generator control units is making them robust enough to provide the necessary detail to the operator in order to properly and safely operate and control the equipment, while having an interface that is simple enough to understand and get the information needed when an error occurs — without extensive training.
Finding the right balance often leads to taking a closer look at which type of control unit is more effective — analog or digital?
Analog and Digital Control Units
In reality, modern mobile generator sets have had “digital” controls onboard for many years. The electronic control units (ECU) that control the engine and generator operation are computers — digital devices. So when we speak of “analog” versus “digital,” we aren’t typically referring to these devices. We are referring to the format in which information is displayed to the operator.
An analog control panel allows the operator to see all the information coming from the generator. Similar to the dashboard of your vehicle, the panel displays key information continuously on gauges or meters. In addition to determining the value of a particular output — amperage, for example — the operator can easily determine how quickly values are changing by watching the needles on the gauges. A needle that isn’t moving indicates a steady state condition. A needle moving rapidly indicates a changing condition, possibly
an indication that something on the generator needs operator attention.
A digital control panel typically uses an LED or LCD display to present information to the operator in the form of numbers or symbols. Because this type of display provides discrete values, it can be more difficult for the operator to determine the rate of change of information being displayed. However, digital displays can typically provide a significant advantage by having more information available than analog displays, which are limited by the number of gauges on the panel. Digital displays can be programmed or configured to display any information being output from the control system.
So, which is more effective for the operator — analog or digital? The debate continues throughout the generator industry.
Difference in Display
Several generator manufacturers offer only digital control panels, while others offer analog as their only option. Though the machine interface will vary depending on manufacturer, digital displays include one point of access, most commonly in digital readout screens, where the operator would need to scroll through multiple screens or menus to obtain the information needed.
With an analog control unit, measurements from the generator are shown through separate meters and gauges that make up the control panel. An operator will find the start/stop switch or button, frequency, voltage and amperage gauges on a typical analog control panel. Depending on the manufacturer, an analog panel can also include a tachometer, oil pressure gauge, water temperature gauge, DC voltmeter, a diagnostic indicator and fuel level gauge. Some will include a run/idle switch to reduce engine wear during startup in extreme cold temperatures. New Tier 4 Interim machines also include an engine diagnostic code reader with indicators and controls for the diesel particulate filter regeneration functions.
All control panels, whether analog or digital, include an hour meter. On a generator with an analog display, the hour history is instantly accessible on the panel, which is an advantage particularly in the rental market. With a digital control unit, the machine must be turned on to get the hour meter reading, which can take 30 seconds or more for the control system and display to start up.
It’s All About the Operator
Through extensive research, operators note a preference for generators with analog panels — it requires little training to understand and is the easiest to comprehend with an at-a-glance reference to monitor machine operation. An operator can determine whether everything is running as it should, whether any indicator lamps are on and whether gauges are in a normal range from 10 ft away from the machine. With a digital readout on a panel, the operator needs to be at the panel to receive the same information as well as to access the needed information from the digital display, which could take more time away from other aspects of the job.
Training Equals Time and Money
Understanding a digital control panel and its functions and modes can provide the operator with more information than the typical analog control unit. But, that requires operator training and understanding of all functions and accessibility through the digital display. Without training on how to properly and safely run the generator and without understanding of a digital panel, a simple mistake could lead to bigger issues — possibly even an emergency shutdown causing downtime on the job. When equipment that is inherently complex to operate, such as a generator, is fitted with challenging controls, operators are going to need more intensive training to protect themselves, their jobsites and the equipment itself. When generator operation information is easy to access, it will be simpler to determine if the machine needs attention. It also cuts down on training time — an important benefit for the rental customer and rental companies.
Don’t Downplay Digital
Operator error with digital control panels may lead to a misconception that generators with digital controls are less reliable than generators with analog controls. Though the interface of the control system may look different, equipment reliability depends more on the manufacturer than it does on the control panel. A digital control panel can enhance versatility with extra features and can be an excellent choice for an operator who is savvy and comfortable with the technology associated with it. As new technologies evolve, consumers are faced with paying a higher price for that technology. Analog may be a more popular choice for generators because digital is perceived to be more expensive. In reality, prices of a digital and analog machine are comparable. With gauges, switches and controllers needed for the interface, the technology with one information outlet is similar in cost.
The Best of Both Worlds
As we look toward the future in terms of control unit development, research shows customers are still going to want information displayed by analog means. They need the at-a-glance monitoring and simple ability to see what’s going on with the machine without taking time to scroll to a particular screen. But when they do need to get more information out of the generator, whether it’s onboard diagnostics or an enhanced level of features beyond what the gauges are displaying, the digital panel will become a requirement.
A future option? A hybrid of both digital and analog will meet the need where analog meters display key information such as frequency, amperage and voltage; and digital displays share more detailed information about engine operation and includes new features such as maintenance history. Until then, the key factor in running a mobile generator safely and successfully is to have a generator equipped with a control panel that is easy to understand combined with a level of individual training for confident and efficient operation.
Todd Howe is manager of global generator products for Doosan Portable Power, based in Statesville, N.C.
