General / Site Survey

It is important to survey a site in detail from three different perspectives for each installation: Electrical, IT and Wireless. The following guide is intended to aid this process, and is presented as a series of questions. There may also be site-specific considerations that this guide does not cover.

Electrical Site Survey

When selecting Electricity Monitors for installation, the following items should be considered:

  • What CT size (aperture diameter) is required? This will be based on the diameter of the conductors to be monitored.
  • Are multiple conductors used per phase (common in some high current 3 phase systems)?
  • What CT current rating is required? What is the maximum current that the system being monitored will experience?
  • What is the distance between the location where the electricity monitor will be mounted and where the CT’s will be connected?
  • Will the CT cabled be threaded through a gland or coiled?
  • Is 2 meters (the standard CT cable length) sufficient to cover this distance?
  • Where will the electricity monitors be powered from?
  • Is the voltage within the range that the device is designed for?
  • Is the location that the monitors are being powered from at the same voltage as the system being monitored?
  • For three phase system how is the load connected?
  • Is variable speed drive starting used – remember to monitor on the supply side of such a device.
  • Is there a neutral available?
  • How will the electricity monitors be mounted?
  • Will the electricity monitors be constantly powered or switched off when the electrical load is not in use?
  • Will they be mounted inside an electrical panel or outside?
  • What method will be used to mount the devices? Adhesive strips / rivets / screws.
  • What breakers will be used, how will they be mounted and are they suitably rated?
  • Will a shutdown be required to connect the electricity monitor?

When installing Analogue / Pulse monitoring devices:

  • Are there ATEX or similar certification requirements for the area where the signal is available?
  • Is the pulse output frequency / width / type known?
  • Is the signal currently in use by a BMS (building management system) or other equipment?
  • Is it known what real-world parameter one pulse represents? Or if is known what the analogue range in a current loop represents?
  • Is the meter that’s being interfaced with the property of a utility company or other 3rd party?

When installing Range Extenders consider the following:

  • When installing range extenders, how will the devices will be mounted? Where will the range extenders be powered from? Is this a reliable and constant power source? How the device is protected (for example with a fused spur)?
  • When installing the Gateway, it is desirable for this unit to be constantly powered – should a UPS be used? Note that this unit needs to be well ventilated and mounted in an area free from moisture and dirt.

IT Site Survey

When connecting the Gateway to a network, consider the following items:

  • Is there a firewall or NAT in operation that could restrict communications from the Gateway? Can this be configured?
  • How are IP addresses assigned?
  • Is access to the internet restricted?
  • How will the Gateway be remotely accessed in the event of a problem?

Wireless Site Survey

The purpose of the wireless site survey is to determine if range extenders will be required to design a stable wireless sensor network. There is a kit available to map wireless signal strength on site available from EpiSensor. This site-survey kit consists of three wireless dongles that mimic the operation of a live system, allowing users to survey wireless signal strength on any site. The signal strength achieved is dependent on distance and the characteristics of the materials in between each device, or the fabric of a building.

The site survey kit includes two “Node Dongles” and one “Gateway Dongle” – these devices act in the same way as a normal Gateway and nodes, but they are programmed with custom software that indicates wireless signal strength via three LED in a traffic light system.

It displays its status as follows:

LED Colour

Signal Strength (%)

Link Quality Index (LQI)

Signal Strength Description

Green

80 – 100

> 200

Very Good

Orange

60 – 80

> 150

Good

Orange & Red

40 – 60

> 100

Poor

Red

< 40

< 99

Bad

Flashing Red

0

0

No network connection

To survey a site with the kit, first power all dongles with the included USB power packs. Position the “Gateway Dongle” in the location where the Gateway will eventually be installed, and move outwards with the “Node Dongles” to the intended locations of each wireless device. If the dongles are arranged in the “1 – 2 – 3 – X” formation, large distances can be surveyed by moving node 1 to position X and so in the required direction.

The position where signal strength drops off, and range extenders are required, should be marked on a floor plan. Also mark up the floor plan with the locations of Battery Nodes, Powered Nodes, the Gateway, Mains Power points and Network Access Points.

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