Kanchrapara workshop of Eastern Railway has developed the first of its kind on Indian Railways, an OHE cum battery powered Tower Car for OHE inspection and maintenance. This Tower Car is the product of an innovation to use old MEMU coaches.
The old MEMU coaches have been suitably modified to suit various requirements such as the provision of an overhead inspection boom, bio-toilet, tool cabinets, crew rest area, roof mounted catwalk, etc. Safety appliances such as an OHE indicator are also provided.
The traction control circuit has been designed to ensure jerk-free start/stop, especially under battery power mode to ensure smooth movement while inspecting the OHE and during measurement and calibration runs.
An important capability of this Tower Car is that will be able to monitor OHE parameters under live OHE, also called “Hotline” monitoring.
Important parameters include contact wire height and stagger.
The Tower Car will be able to run continuously under battery power for 2.5 hours and intermittently for 5 hours. The tower car is provided with a dual bank of lead acid batteries for propulsion and the circuit design is such that excess load on the batteries is prevented through protection devices.
Features of Navonmesh:
- Low breakdown time compared to conventional Diesel Tower car.
- Low height roof (3.6m) for hydraulic platform
- Catenary and contact wire drum storage
- Roof ladder with OHE indication lighting
- Both end driving with vestibule
- Max speed 90kmph in OHE mode, 50kmph in battery mode
- Both side hook with screw coupling
- Hotline checking of OHE
Battery features:
- 56 nos. lead-acid batteries (8 volt, 500AH) have been distributed in 2 battery banks. Each battery has voltage 112V and capacity 1000AH.
- Both battery banks can be connected in parallel combination and series parallel combination.
- Speed control is achieved by altering Series-Parallel combinations of both traction motors and batteries to vary voltage per traction motor from 23V to 216V.
- Overload protection relay with battery current setting of 550Amps has been provided resulting in automatic notch regression.
- Earth fault protection to enable tripping in OHE mode and auto regression in battery mode.
- Battery over discharge protection for battery voltage less than 105V with push button acknowledge switch.
- Time delay relay provided between notches in battery mode to limit the surge current in batteries to maximum 200 Amps to prevent heating up of batteries.