A site-assessment method for multi-site voltage stabilization

The technical problem

An organisation with many sites often buys voltage stabilization one site at a time. Each purchase is sized from whatever information is to hand, by whichever contractor is involved. Over time the network fills with equipment of different ratings, configurations and documentation, and nobody can say with confidence whether each unit suits the site it serves. When a problem occurs, the facts needed to investigate it are scattered.

The aim of a programme is not identical equipment everywhere. Sites differ in supply, load and layout. The aim is one controlled method for assessing a site and one logic for turning the assessment into a configuration, so that differences between sites are deliberate and recorded.

Conditions that vary between sites

Even sites of the same format usually differ in:

• Incoming supply: distance from the distribution transformer, the condition of the local network, and the time of day at which voltage is lowest
• Load: the mix of refrigeration, air conditioning, lighting and IT equipment, and how much of it runs together
• Phase balance: how single-phase loads are spread across the three phases
• Backup supply: whether a generator feeds the same board and how it behaves on changeover
• Space and access: the room or area available, ventilation routes and access for maintenance

A method that records these conditions in the same way at every site allows the sites to be grouped. Sites inside the same group can share a configuration; a site outside every group receives a recorded variation.

Solution principles

One assessment record

Use the same assessment record for every site: load schedule, measured voltage over a representative period, phase readings, backup arrangement, and installation photographs taken with permission. Where a value is estimated rather than measured, the record says so. A short, consistent record is more useful than a long one that differs from site to site.

Configuration logic, not a single rating

Define a small number of configurations, each with the input window, rating band, phase arrangement and installation format it covers. Servo voltage stabilizers are typically available up to 500 kVA in single-phase and three-phase formats, which allows the configuration set to span small and large sites within one equipment class. The logic states which measured conditions place a site in each configuration.

Recorded exceptions

When a site does not fit, the variation is recorded with its reason: a wider input range, an unusual load, a space constraint. Exceptions are reviewed centrally rather than resolved on site, so the standard does not erode through informal changes.

Consistent identity and records

Each unit carries an identity that links it to its site, configuration and documents. The same identifiers are used in commissioning records and service requests, so that a fault report from one site can be compared with the rest of the network.

Constraints

A method depends on the quality of its inputs. Short or unrepresentative voltage readings can place a site in the wrong group. Sites where the electrical installation itself is faulty, for example with poor earthing or overloaded cables, need that corrected before stabilization is considered; a stabilizer does not correct installation faults. Where a site cannot be assessed safely or supported responsibly, it should be left out of the programme until it can.

Rollout timing is also a constraint. Delivery, installation and commissioning responsibilities differ between new sites and refurbishments, and should be stated per site rather than assumed for the programme.

Inputs needed to start

• A site list with format, location and the stage of each site (new, operating or under refurbishment)
• Load schedules or connected-load estimates for representative sites
• Any voltage recordings or complaints already held
• Existing stabilization equipment and its condition, where present
• The organisation's ownership of specification, installation, handover and service

Next step

The corporate multi-site pathway sets out how responsibilities are divided at each stage. To begin, summarise the site list and the representative data in the enquiry form; the review proposes the assessment record and the first grouping, and lists the facts still needed.