Today, AC and DC fans are required to do more than just cool and control airflow in white-good applications. From refrigerators and freezers to convection ovens and range ducts, home appliance manufacturers need high-performance, energy-efficient fans and fan trays with variable speed, remote monitoring, low noise levels, and wider operating temperature ranges—all while reducing initial installation costs. AC fans, DC fans and blowers are now available with features that meet the demands of low noise, low power consumption, improved functionality and high reliability.
Smarter fans
Designs using fans with “smart” controls optimize fan performance while minimizing power consumption. Intelligent thermal controls can reduce power consumption by up to 30% while reducing noise levels as fans run at full speed only when needed. Smart fan control options can also include tachometer output, airflow monitor (as an additional accessory), locked rotor alarm, pulse width modulation (PWM) input and constant speed control. These intelligent control options allow end users to better monitor their product operating temperatures and fan airflow while ensuring fans are operating properly and under optimal conditions.
For example, the tachometer output provides designers with an accurate way to monitor and report the speed of a fan and indicate if the fan speed falls below a specified speed. This can be used as an alarm trigger or indicator by monitoring fan speed to determine relative temperature. Typically, the tachometer output option is available as either a 5V TTL signal or an “open collector” signal.
Airflow monitors provide a cost effective method of monitoring and maintaining proper airflow in AC and DC fan/blower applications. These modules can indicate airflow or lack thereof with a visual LED and/or an audible alarm when airflow drops below 8.2 ft/s due to fan filter clogs or fan blade interference. The airflow monitors clip or clamp to any grill, are field upgradeable, and can be installed perpendicular to the front or inlet side of the fan.
With a long service life of more than 100,000 cycles, airflow monitors are IP20 rated, NEMA 1 certified and have an operating temperature range of -20°C to 50°C. DC fans and fan trays can be equipped with locked rotor alarms that indicate whether a fan is running or stopped by transmitting a fail-high or fail-low output signal, thereby minimizing fan downtime and avoiding an overheating situation will. A PWM option also allows users to digitally control the speed of the fan via an existing bus system or PLC.
AC fans or fan trays with thermal speed control use a thermistor-controlled circuit that increases fan speed only when the temperature rises above a specified setpoint. This reduces overall power consumption by lowering the fan speed when the temperatures inside the chassis are below setpoint. Thermistor control circuitry can be mounted directly in the fan hub or remotely mounted via a connector cable and positioned anywhere in the housing, giving designers the flexibility to regulate fan speed based on ambient temperature within a specific range. The constant speed function detects a variable input voltage that causes fluctuations in the output power and keeps the fan at a constant speed regardless of input voltage fluctuations.
Decrease the volume
Low noise fans in refrigeration units, chillers and range hoods are used to perform various functions while reducing the noise typically present in older product designs. Quiet fans are often chosen for refrigeration and wine cooling applications to prevent condensation but do not contribute significantly to the audible noise level. Condensation can form on the inside of these units, forming not only on the glass but also inside the case itself. Using an internal IP55 rated fan creates just enough air movement to prevent condensation. The same situation exists in store refrigeration units. Available in both AC and DC configurations, the low noise fans are used in these applications to not only prevent condensation, but also to minimize noise levels and reduce power consumption.
Electronically commutated fans
Electronically commutated (EC) fans use a brushless DC motor with a single or universal AC input. EC fans feature voltage conversion within the motor to provide a two-speed, low-power fan. In addition, EC fans are programmable for even more energy savings. EC fans are well suited for large cooling units and chillers, providing an energy efficient cooling solution with low power consumption.
Toughest Environments
Components exposed to harsh environments including high heat are prone to failure over time, and fans are no exception. The classification of the insulation system is based on the lowest rated component in the system and in many cases can be the fan. The materials and parts specified in the design that affect the insulation class include the motor winding, the wire and the insulation of the wires, the enamel coating of the magnet wire, and the visible parts of the fan or fan tray such as the frame and impeller.
In white goods applications, AC and DC fans must be able to operate in extreme temperature ranges, from cold freezers to extremely hot convection ovens. Various materials and designs are available to achieve the performance and reliability required for a variety of applications.
A high temperature fan with a higher insulation class B or F construction will often eliminate or reduce premature failures caused by insufficient airflow in hot areas. AC fans are commonly used in high temperature applications such as oven control assemblies and forced air convection units. Class B insulation temperature is specified at 130°C while Class F insulation temperature is specified at 155°C. These maximum temperatures that the plastic and insulating materials are rated for include the normal temperature rise of the fan, so care must be taken not to exceed these ratings in these types of applications.
All-metal AC fans address size, performance, and compatibility issues in the most rugged white goods applications such as HVAC and commercial fryers. All-metal fans are resistant to high temperatures and corrosive compounds, which can allow longer life expectancy in harsher environments.
Customization and added value
Fan technology allows manufacturers to customize their fans, fan trays, and blowers to meet application needs. Whether it’s airflow, noise level, alarm output, IP rating/NEMA protection, or a specific function, fan manufacturers can meet the required specifications.
Not all fan manufacturers offer on-site connector, harness, and bracket assembly, which simplifies the fan installation process for white goods manufacturers. Fully assembled and tested fan trays offer white goods manufacturers additional benefits by lowering supply chain costs, reducing material lead times, reducing SKU counts, reducing parts inventory, simplifying installation, improving quality and lowering overall production costs. Not only does the tray offer a complete solution, it also reduces part numbers and inventory of refrigeration parts from ten to one. Tray manufacturers like Orion Fans also assemble, test and ship if required, further reducing long lead times.
Conclusion
With more features available than ever before, including higher temperature ranges, speed controls, and tachometer output signals, to name a few, home appliance manufacturers are using fans to provide enhanced functionality, maximize energy efficiency, and reduce end-unit costs.
