Fanless NVR (Network Video Recorder) System for Metro Lines

Introduction

In 2017, we were contacted on behalf of a well-known public transportation company in Northern Italy. The request was for the provision of an NVR (Network Video Recorder) system for video recording in the stations of a metro line.

Metro lines are subject to very stringent requirements, both due to safety regulations and the need for compatibility with existing systems.

The client wanted to install a robust video recording system in the cabinet rooms located in all the stations of the metro line, to which all data streams from the IP cameras to be installed along the route would converge. The requested NVR system needed to persistently and fault-tolerantly record data, as well as allow remote network access for monitoring and video surveillance.

Client Requirements

The client imposed very stringent requirements on CJB. Among them:

• Operating at 12V DC
• Windows IoT Embedded LTSC operating system
• Completely fanless and dust-proof system
• Core i7 processor
• Capability to interconnect and manage data streams for a maximum of 32 concurrent IP cameras
• Hardware RAID 4x4 system
• Removable hard disk array of 4 x 4TB, guaranteed 24/7 for NVR usage
• All components certified for temperatures of 0–70°C
• Continuous operation in ambient temperatures of 50°C
• Internal NVR peak temperatures never exceeding 60°C

Solution Development and Cost Containment

The project was a joint effort with a local company that supplies systems for public enterprises, which operated through tender bids and subcontracting. For this reason, the project had to balance compliance with all requirements while keeping costs as low as possible.

Custom Project or OEM System Modification?

If the client does not have a stringent budget limit, a system like the one described can be developed from scratch, especially if a specific, customized, or distinctive external design is required.

In this scenario, however, the NVR was to be installed inside an electrical cabinet, not visible from the outside.

Heat Management

A fanless system that must also operate at high ambient temperatures (>50°C) reliably requires very accurate thermal management. Typically, this type of system comes at a high cost.

Additionally, the client specified that the installation cabinet would be very dirty and dusty, further complicating heat evacuation.

To contain costs and win the tender, CJB activated its supply chain and identified a suitable fanless OEM chassis that could be modified to operate in high temperatures and dusty environments.

In collaboration with a partner based in Taiwan, CJB designed the heat management system based on liquid heat pipes, capable of transferring heat from internal components (including HDDs) to the NVR case and dissipating it externally through finely finned surfaces. The entire system remained sealed to prevent dust ingress, despite one of the requirements being the removability of the hard drives.

The radiator, compared to more common designs, was specifically engineered to retain as little dust as possible, ensuring excellent cooling performance even when dusty.

To guarantee maximum reliability for the hard drives, the housing frame and removal slide were thermally managed like the rest of the electronics.

Despite these modifications, the cost of the system remained contained because CJB was able to reuse the standard electronic housing frame already present in the OEM system provided by the Taiwanese partner.

Fans in a Fanless System? The Anti "Heat-Soaking" Solution

A common problem with fanless systems is the temperature disparity between components directly cooled by heat pipes and those not touched by them. Over time, components subjected to stagnant hot air can deteriorate, leading to premature failures, a phenomenon known as "heat-soaking."

To create more uniform temperatures within the system, CJB used heavy-duty 24/7 fans to eliminate stagnant air in areas not directly cooled by heat pipes. The use of fans within a fanless system may seem counterintuitive, but since the system is sealed from the outside, the operation of the internal fan is assured as it works under ideal conditions, free from dust or moisture that could impair its performance. A powerful and continuous airflow is created within the system, helping to equalize the temperature by transferring some heat to the metal casing (chassis).

Stress Testing of Prototypes

A high-reliability fanless system must be tested under the most extreme operating temperatures for which it is guaranteed.

CJB has a climatic chamber capable of subjecting electronics and large devices to complete and prolonged thermal cycles.

Additionally, CJB possesses infrared thermal imaging devices to study heat distribution on radiant surfaces.

The NVR system was tested for 96 hours at the extreme guaranteed temperatures and demonstrated excellent tolerance to these environmental conditions.

Reliability Data, 7 Years Later

The tender was won, and CJB provided over 100 NVR systems to the client.

After 7 years of continuous 24/7 operation, the fault rate of the system is, to date, practically 0%, excluding normal and expected maintenance of the hard drives, which are considered consumables with a limited lifespan.

An Integrator Must Be Able to Adapt OEM Solutions

It is not always feasible to create 100% custom solutions, both due to higher costs and longer design times.

This project demonstrates how important it is for a System Integrator like CJB to be able to customize existing OEM systems.

CJB has a wide network of partners and suppliers worldwide, with whom it collaborates to customize OEM systems to meet the specific needs of its clients.

If you need to develop or integrate recording or surveillance systems in public or private environments, please contact us for more information.