19" rack-mounted fan trays supplied to US defence contractor

Requiring low noise levels, low current consumption and high reliability, Verotec designed a custom control board which sequentially powers each of the fans in order of importance. This minimises the initial inrush current. Over-specified for the required airflow, the fans can produce this airflow running at just 70% full speed. This facilitates an extended MTBF, as well as reduced noise and current consumption.

User-controllable to support system deployment around the world, the maximum fan speed  is controlled by an embedded microprocessor using PWM technology. A custom input air ducting system brings air from the front of the rack into the bottom of the fan tray. EMC integrity is provided by the honeycomb grill, while the removable air filter is mounted at an angle to maximise particle removal without restricting airflow.

Since reliability is a key factor, a warning signal will trigger for three separate events: power loss to the fan tray; a fault on the controller board itself or if the speed of any fan falls below 20% of maximum. As the main processor board is deemed to be a critical component, if the speed of the fan cooling this falls below 20%, the relay latches into the alarm position. The alarm relay will return to its normal position when the speed increases above the 20% threshold, if triggered by any of the other five fans.