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EU07 Simulator English forum / Odp: Why trains must start with two pantographs raised?
« dnia: 14 Października 2022, 17:12:55 »
Mostly passanger trains need that, because there is signficant power draw around 50 - 150A from 3 kV DC OHL to feed carriages with power to charge their batteries, power A/C or heater and feed electric sockets / lights. This current is quite small consumption at travel speeds, however when standing at one place it can cause local overheat of overhead lines, which can in worst case lead to its rupture and teardown. Halving that current by raising second pantograph reduces waste heating power to 25 % (P = R * I^2) which prevents this from happening.
EMUs and all cargo trains pulled by thyristor / IGBT driven locomotives (like ČD 163, Traxx, Taurus 1216) do not require this procedure as their standstill power consumption is much smaller and ammount of taken current raises gradually with increasing speed instead of burning "surplus" power in resistor bank like in for example EU07/201Eo/ČD 181, and so on. Light cargo trains pulled by locomotives with resistive regulation like ČD 181 also do not need both pantographs raised as their power draw at standstill is miniscule. For instance ČD 181 with all auxiliary devices running (fans, both compressors on and 48V DC network convertor) barely draws 50A. However as for what I heard from ČD Cargo locomotive engineers, you are not supposed to exceed current draw 200A per pantograph below 5 km/h, so they raise both pantographs anyways to be sure.
Here in Czech republic this is being done on 3 kV DC routes. On 25 kV 50 Hz routes this is not mandatory as currents are smaller by magnitude and barely exceed 20A at standstill assuming power factor is near 1.
EMUs and all cargo trains pulled by thyristor / IGBT driven locomotives (like ČD 163, Traxx, Taurus 1216) do not require this procedure as their standstill power consumption is much smaller and ammount of taken current raises gradually with increasing speed instead of burning "surplus" power in resistor bank like in for example EU07/201Eo/ČD 181, and so on. Light cargo trains pulled by locomotives with resistive regulation like ČD 181 also do not need both pantographs raised as their power draw at standstill is miniscule. For instance ČD 181 with all auxiliary devices running (fans, both compressors on and 48V DC network convertor) barely draws 50A. However as for what I heard from ČD Cargo locomotive engineers, you are not supposed to exceed current draw 200A per pantograph below 5 km/h, so they raise both pantographs anyways to be sure.
Here in Czech republic this is being done on 3 kV DC routes. On 25 kV 50 Hz routes this is not mandatory as currents are smaller by magnitude and barely exceed 20A at standstill assuming power factor is near 1.
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