Frequency Controlled Switches

These are load control devices for off-grid power systems with renewable generation and generation sets or inverters which produce a variable frequency supply.

Used to switch on additional loads to take advantage of surplus renewable generation which cannot be stored. They respond to a rise in the system frequency caused by battery inverters signalling a high state of battery charge, or by low load on a generator with frequency droop.

Each switch will control one appliance and is wired into the cable supplying the appliance. They require no user intervention and will automatically switch the appliance on when the system frequency is high and switch it off when the frequency is low. The frequency setpoint can be adjusted during installation.

They incorporate a number of features to ensure stable operation of an islanded power system:

• Once the frequency goes above the switch-on setting there is a delay before the appliance is connected; the higher the frequency is above the setting, the shorter the delay.
• The switch-off setting is a lower frequency than the switch-on setting to ensure stability.
• Once the frequency goes below the switch-off setting there is a delay before the appliance is disconnected; the lower the frequency is beneath the setting, the shorter the delay.

Can control loads up to 13A (3kW at 230V; 1.5kW at 120V). The most appropriate loads are heaters (water heaters, storage heaters, space heaters). Appliances with pumps are not appropriate due to the potential for rapid switching of loads.

The FCS-F1-B version is faster acting with closer frequency settings to provide more certainty of the total load that will be applied at a given system frequency for larger power systems with multiple switches. Usually only used for example, for controlling large wind turbines in off-grid systems (available to special order only).

The AC•THOR is a Photovoltaic-Power-Manager for hot-water and space-heating, providing linear control of electric heatsources depending on excess PV power and heat demand. It communicates via ethernet with inverters, battery systems and smart home controllers and receives information on how much photovoltaic energy is available.

In off-grid systems it can respond to frequency rise to divert surplus energy once the battery is full into heating loads.

Includes:

• 0-3kW linear output.
• 16A relay output.
• Colour touchscreen display

• Warranty: 2 years
• Made in Austria

The AC•THOR 9s is a Photovoltaic-Power-Manager for hot-water and space-heating for use in 3-phase systems.

Expanding on the features of the standard AC•THOR this 9s version can deliver up to 9kW, has 3 controllable outputs and is suitable for 3-phase immersion heaters (with common neutral conductors) or with three separate 3kW single phase heaters run on separate phases.

Includes:

• 0-9kW linear output
• Colour touchscreen display
• Warranty: 2 years
• Made in Austria

For use in off-grid systems to use surplus energy once a battery has become fully charged.

The ELWA-AC-F detects frequency rise of the inverter, if there is excess energy available and uses it for heating water.

Advantages

• AC ELWA-F uses energy that cannot be stored in the battery
• Linear power control 0 - 3.000W for maximum self-consumption
• The AC ELWA-F needs no communication cables to the inverter
• Sinusoidal current consumption (no thyristor)
• For AC off-grid systems with frequency-shift inverters eg. Sunny Island & Victron