Winter is coming: guarantee fleet availability with smart battery alerts

Post by Pierre Gérard, data scientist at Railnova
Oct 23, 2017

Winter is coming

Winter is coming, and lucky for us we don’t need to worry about white walkers, but we do have to watch out for an increase in battery failures on locomotives due to the cold and severe weather conditions.

Railnova helps operators to intervene before a battery failure happens, by continuously monitoring the locomotive and its battery (even when the locomotive is turned off) and by sending automatic alerts when we detect abnormalities. As a result operators are able to avoid delays or cancellations, and possible damages to the battery.

Building reliable alerts

The Railnova battery alerts are based on the inference of the battery characteristics observed in the past. We’re inferring the nominal voltage of the battery both when it is charging and when the locomotive is powered off, to gather the most accurate and complete data set to base our alerts on.

We then find, using expert rules based on the usual behaviour of the voltage of a decreasing battery, a threshold below which we believe the locomotive would not start.

On top of that, we filter incoming noise or bad measurements automatically in order to avoid false positive notifications to be sent out. The alert also detects short drops in battery voltage due to circuit breaker trips. When such a short drop occurs, we do not send the depleting battery notification.

Another example: the Data Inspector graph below illustrates that whenever an asset starts, a voltage drop (due to a higher current consumption) occurs. In many cases, this situation would have triggered a false positive alert, as the battery voltage drops below a certain level. Railnova however takes this, and many other scenarios under consideration and only triggers an alert when necessary.

The data-driven part of the battery alert is auto-updated, to take new locomotives and variation in the fleet into account. The combination of expert knowledge and data-driven knowledge make these alerts far more reliable than others.

Type of battery alerts on Railfleet

There are multiple types of battery notifications that you can send to your colleagues and stakeholders so they can take action in time. For example, you might want to be warned when the battery level drops below a certain level, or when the battery isn’t charging when it needs to be:

1. Low battery level: warning

This alert notifies you when the battery tension of one of your assets is dropping under its usual level at a non-critical pace. This gives you the chance to react within the next few days (the exact timespan will depend on your asset and the battery capacity) to make sure that your team is able to start the locomotive for its next trip. (Set up this alert on Railfleet)

2. Low battery level: critical

The critical low battery alert works in a similar way as the warning low battery alert: it warns you when the battery tension of your asset us dropping under its usual level. However, when this specific alert is triggered you only have a couple of hours to react before the battery tension would be too low to start the locomotive. (Set up this alert on Railfleet)

3. Asset in charging zone but not charging

Whenever an asset is located in a charging zone but hasn’t been charging for more than two hours, you’ll receive this alert. This gives you time enough to inform your teams on the ground before the asset is supposed to depart for its next trip. (Set up this alert on Railfleet)

4. Asset parked on battery for more than 2 hours

This alert helps you detect that the battery is discharging when the locomotive is powered on, while the motor is not running and the locomotive has no external power source. Subscribing to this alert helps you to take immediate action and avoid completely discharging the battery. (Set up this alert on Railfleet)

All these battery alerts can be dispatched to a fixed set of people such as a specific fleet manager, or your technical team. But, in order to make fast interventions possible, they can also be dispatched by the geographical zone the locomotive in question is located in. That way the people closest to the locomotive can intervene before a failure happens and are able to avoid delays or cancellations.

Interested in receiving battery alerts for your fleet and avoiding delays or inline failures yourself? Contact us or meet us at the London Rolling Stock Maintenance Summit on 6 and 7 December 2017, we’re happy to help!

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