Power demand for specially developed jointing techniques and ancillary services is met by a 10 kVA, 110-volt, 50 Hz, single-phase generator, mounted on a long-wheel-base Land Rover and driven by the vehicle engine through a standard gear box power take-off. The generator is a drip-proof, screen-protected, self-excited and self-regulating type meeting the requirements of BS 2613.
A 30.5m extension lead is accommodated on a live centre
reel and feeds a remote switching panel which is lowered into the manhole or
jointing pit. The switching panel incorporates an ammeter, five 15-amp
socket outlets and two 40-amp socket outlets. The 15-amp outlets are
individually switched and the 40-amp outlets are of a load-breaking,
Guarding against overload is provided by a double-pole circuit breaker fitted on a control box which also houses an ammeter and a voltmeter. The control box is fitted in the Land Rover adjacent to the generator.
Regulation of generator voltage is such that the voltage does not fall below 110 volts nor rise above 120 volts at any condition of load for power factors within the range unity to 0.8 lag. The generator is centre-tapped at 55 volts and the centre-point connexion is through a third slip ring which is fully insulated from the generator frame. The third (earth) pin on all outlets is connected to the 55-volt slip ring. All generator connexions are isolated from the vehicle.
The vehicle has a 2.6-litre, 6-cylinder petrol engine and
a special engine-speed governor is fitted to provide rapid response to
changing generator load conditions. An engine oil cooler is fitted to
allow running for long periods with the vehicle stationary and the engine
exhaust is mounted vertically to carry exhaust gasses clear of the jointing
area. A hard-top body with side-hinged rear door is fitted and the
door is mounted on lift-off hinges so that it can be removed easily if
required to erect a tent close to the rear of the vehicle.
Last revised: February 09, 2022