PS50 secure power supply is playing a real key role in Easergy T300 solution, as it ensures that the system is available at any time, especially when Mains power source is down.
One of the main functions is to charge the battery when mains is present, and to monitor periodically the battery status very precisely.
Thereby the Control Center is warned when battery needs to be replaced, so ensuring the Remote Terminal Unit will be operational in case of a later electrical fault on Medium Voltage distribution network.
Hereafter is a description of how all this works
The PS50 power supply unit supplies the back-up operating voltages for
- MV switch motorisation
- Transmission equipment, such as radio
- Easergy T300 modules
- Control units, such as protection relays and Fault Passage Indicators (FPI)
Each output is separately protected, and PS50 ensures a 10kV insulation from LV input.
A battery ensures the operation of the whole substation in the event of loss of the mains supply. The power supply unit ensures its charge and monitoring (regulated and temperature-compensated charger).
Battery end of life detection is achieved through a periodic test every 12 hours, measuring battery internal resistance, and issuing alert in case of 2 successive failures.
The product is communicating with HU250 head unit using Modbus protocol, so enabling to collect the results and to warn Control Center for battery replacement.
- It is of outmost importance to replace batteries within days after alert reception.
PS50 and associated battery ensures backup capability for a control and monitoring system of an MV Equipment up to 16 MV functions.
E.g. it will supply power to following modules for several hours after loss of mains:
- 1 HU250 + a 3G modem
- 16 SC150
- 1 LV150
Actual expected autonomy may be calculated using the excel autonomy calculation sheet.
Two commercial references are available to address two voltage level for MW switch motorization:
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Product Name
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Commercial reference
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Commercial designation
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PS50-24V
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EMS58587
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Back-up Power supply - 12V, 24V output
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PS50-48V
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EMS58588
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Back-up Power supply - 12V, 48V output
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PS50 settings may be adjusted through HU250 webserver.
Regarding the battery, the charger permanently maintains the battery in the range of voltage and current specified by the battery manufacturer, as follows:
- A limit of discharge threshold is defined, as a minimal voltage (value configurable and defined for each type of battery by the manufacturer). When the battery voltage goes below this threshold, PS50 stops all activity to avoid battery deep discharge resulting in its deterioration
- The battery charge is carried out at constant voltage (value configurable and defined for each type of battery) in order to reduce the total charging time. The total charging time ranges between 10h (without load) and 24 h (with maximum load).
- When the battery is charged, the charger will keep charging at constant voltage by applying the load constant voltage (adjustable according to the manufacturer).
- The charging voltage of battery at constant voltage will change depending on the temperature with a compensation that is configurable (mv / ° C).
- The charger limits the maximum charging current of the battery so that it never exceeds the setpoint, adjustable, fixed by the battery manufacturer.
- The charger supervises the voltage applied to the battery during the charge process and avoids overvoltage even in case of internal failure
Note: By default, all the settings are set to the values provided by Yuasa for SWL and NPL batteries.
(e.g. 3mV/°C/cell for temperature compensation)
Jean-Luc BATARD
Distribution Automation Senior Application Engineer
