One of the most common issues that we respond to involves power supply. Sometimes its simply a case that someone has disconnected the school’s server or Protex Pro Appliance box. Other times its going to take a bit more than plugging it in or ‘turning it off and on’ to get things going again!
Just after 5pm one Monday in August we had a call from a primary school in Coventry. They had no Internet. The school’s on-site technician reported that:
“The existing PDU (Power Distribution Unit) installed in the rear of the main network cabinet is faulty. The isolation switch is no longer lighting. The PDU also caused the power supply in the E2BN appliance to ‘pop’. This has caused the site to lose Internet access.”
A PDU is a device fitted with multiple outputs. It distributes electric power, especially to racks of computers and networking equipment located within your server cabinet. Replacing a PDU is not difficult. The school technical team were able to source a replacement PDU and planned to install it the next day. The E2BN Appliance however, needed a specialist.
One of our wonderful technicians, Martin, set off bright and early on Tuesday morning with replacement equipment. The school’s technician replaced the PDU, whilst Martin confirmed that our Appliance’s power supply had been destroyed by the faulty PDU.
After replacing the power supply, Martin discovered that the power surge had returned the Appliance its factory settings. He restored the settings from our back up. Then carried out a full resilience power loss simulation, twice, to confirm full functionality in case of any future outages. Martin also tested the local network DHCP and DNS, carried out a speed test and confirmed that Internet browsing and filtering profiles were all working. The school’s Internet was back up and running in two hours.
Why it happened
Back at the office, Martin analysed the damaged PSU (power supply unit). He confirmed that a very high voltage surge had caused the damage.
The photographs below show the damaged components.
All Appliance PSUs undergo high voltage testing and certification during production. As part of the built in surge protection these components are designed to withstand voltage peaks up to 600V. If a surge exceeds 600V, the protection circuit disconnects from the power to prevent any further damage to the equipment.