Case Study:  Power Testing Ltd Job Ref No.9961

Client: Thames Water Utilities. (Water Utilities)
Location: Store Road Pumping Station, Silvertown, London

Scope of works:

Power Testing Ltd were engaged to design, supply and install in order to complete the following:

  • 11kV Switchboard Works
  • Off Load eight sections of 11kV RMR Switchgear.
  • Build two 11kV RMR four panel boards.
  • Test and Commission.
  • Remove existing 11kV Switchboard.
  • Lifting / Shifting Old and New.
  • Cabling.
  • Cable Testing.
  • Excavation.
  • Earthing Modifications.
  • Jointing.
  • Supply / Install six Termination Kits.
  • Supply 2 x four panel Ringmaster Switchboard:-

MVAA Works

Provide and install a new wall mounted panel to house Transformer Pressure and Temperature (MVAA) relays relocated from 4 existing transformer feeder circuit breakers and current transducers relocated from all 6 existing circuit breakers, including all necessary panel wiring, terminals and labelling.

Relays and transducers from circuit breakers, which are out of service due to previous damage, can be relocated immediately to minimise the changeover time between switchboards. Note terminals between CT secondaries and current transducers must be clearly labelled and provided with shorting links.

Transfer Intertrips

Transfer intertrips and DC tripping supply to the 4 new transformer feeder circuit breakers (shunt trip coils and auxiliary contacts) as follows:

a. Restricted Earth Fault (from MCAG14 relay on respective LV ACB)
b. Transformer Pressure (from relocated MVAA relay see item 2)
c. Transformer Temperature (from relocated MVAA relay see item 2)
d. Intertrip LV ACB on opening respective HV CB
e. LV ACB permit to close when respective HV CB is closed

Transfer Current Transformers

Transfer 6 off load current signals (2 incomers, 4 transformer feeders) from CT terminals in new switchgear via current transducers in new wall mounted panel to analogue signal junction box in HV switchroom. Incomer voltage signals are no longer required.

Differential Protection

Decommission transformer differential protection system including removal or shorting out of current transformers in the LV Switchboard.

Mimic / PLC Works

Transfer HV circuit breaker auxiliary contact signals for the hard-wired mimic in the LV switchroom to the new HV switchboards. Modify the mimic to accept circuit breaker auxiliary contact signals from the two new switchboard interconnector circuit breakers. Carry out any necessary modifications to the mimic PLC (Genius GLC Fanuc) to accommodate these signals. Incomer voltage signals are no longer required.

PLC / Telemetry

Investigate pumping station process PLC and telemetry signals to ascertain impact of HV switchgear change. Make any necessary changes to ensure continuation of existing functionality and visibility / alarms via telemetry.


Carry out commissioning and provide full set of documentation including:

f. Off site and on site test results
g. As constructed drawings for HV switchgear, new wall mounted relay / transducer panel and hardwired mimic panel.
h. Cable schedule and block diagram showing interconnections between HV switchgear, relay / transducer panel, battery charger, analogue signal junction box, LV switchroom mimic panel and LV switchboard.
i. Electrical Single Line Diagram.

Power Testing Ltd has a long-standing relationship with this client.

The project was highlighted as needing to take place and a budget released by Thames Water Utilities.

Power Testing Ltd were engaged to provided a quotation in a competitive bid.

On successful award Power Testing Ltd assigned a project manager who attended site and surveyed the scope of works ensure the client receivedexactly what he required. Materials were ordered.

During various phased organised shutdowns Power Testing Ltd engineering team attended site.

The following staff were scheduled and attended:

Power Testing Ltd completed all works as detailed within the scope of works.
The contract value not including others 118,896.30
These works were programmed to be completed with in six weeks. The works were not continuous and involved detailed planning with EDF Energy and Thames water operations to meet business needs/requirements.

Power Testing Ltd completed all works under PTL internal budget and profit margins and within the shutdown window. All quality objectives were met and no Health & Safety or Environmental incidents were recorded.