How it works
Using a split core current transducer, WINDCRANE can measure crane power consumption without being directly connected to high-current components.
When you know the actual power consumption of a crane, electric power supplies can be sized based on real current input instead of a peak value that is never reached. You can also negotiate with the utility company and contract the actual power required by the crane, instead of its full rated power.
Consider the following example, where the tower crane is rated for 400 amps but the actual current drawn remains below 120 amps. In this case, contracting a 400 amp connection with the local eclectic company represents a waste of money.
Analysing Tower Crane Power Consumption with Smart Data
The following chart displays crane current (horizontal axis), and the number of hours the crane operated at that consumption level (vertical bars). As you can see, the crane remains idle most of the time with a current input below 5 amps. Even when the crane operates, the current tends to peak at 70 -100 amps most of the time, not even getting close to 400 amps.
The WINDCRANE Power Monitor can also be used to determine how much electricity is being consumed by a tower crane over time. The chart above covers 250 hours of crane operation, where the accumulated electricity consumption reaches 700 kWh.
- Electricity consumption can be multiplied with the kilowatt-hour price charged at the project site, to determine the energy costs associated with crane operation.
- By knowing the kilowatt-hour input, you can also determine if a tower crane is energy efficient with respect to the amount of work completed.
In this case, the tower crane is lifting loads 26% of the time and travelling 8% of the time. The crane is idle the remaining 66% of the time.
When the power consumption of a crane has been measured accurately, the grid connection can be sized optimally. If the project involves a few lifts that will bring the tower crane close to rated current, portable power supplies can be used. Some examples include:
- Diesel generators
- Flywheel generators
- Large-scale batteries
Generally, this is less expensive than having an oversized grid connection, which will almost never be used at full capacity.
Using Crane Power Consumption Data for Safety Purposes
Crane energy consumption data not only shows the electricity input, but also the times when the unit was operating. This data can be analysed along with weather monitoring data, to determine if the crane has been used duringunder high winds. The following table provides an example, correlating crane current with measured wind speed:
The table above suggests that the crane was being used under dangerous weather conditions. The maximum wind speed for tower cranes is 38 mph in the UK, and higher values can be found on the table. Ideally the crane should only be drawing idle current during these high-wind periods, but currents ranging from 20-30 amps have been measured when wind speed exceeds 40 mph.
Access your data online remotely at anytime with Windcrane.
