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• About EMMA
• How EMMA Works
• Benefits
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• Models & Sizing EMMA
• Installing EMMA
• Photos
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Sizing EMMA

Please note: This page is deliberately long to give you a good overview of all the models available.

Suitable for Single and Three Phase Connections

EMMA is available in single phase (SP) and three phase (TP) ranges. EMMA's modular "Cascade" design allows you to manage loads from 1 to 300 kW. EMMA is designed for grid-connected microgenerators.

GVS versions - avoid network upgrade costs

GVS (Grid Voltage Stabilisation) versions of all EMMAs are available. EMMA GVS allows you to connect any size generator to the grid as it controls how much electricity is exported, so allowing you to avoid expensive network upgrade costs.

• An EMMA SP15 provides up to 15amps of current, suitable for most domestic situations with a standard immersion of 3kW or below.
• Anything above 3Kw and below 9Kw will require an SP15/30 or SP15/45.
• An EMMA SP15/45 provides up to 45amps of current, suitable for multiple 3kW immersions up to a total of 9 or 10 Kw.
• The EMMA TP45 and TP45 Gaia are suitable for three phase connections and are often installed on small commercial, schools or leisure buildings with a reasonable heating/hot water load. The TP45 Gaia is optimised for use with Gaia wind turbines
• Opt for a GVS version on sites where the DNO limits how much electricity you can export

• These PWM controllers act effectively as one controller ramping the first connected load up and down. As more power is available the SSRs are switched on sequentially - or in cascade fashion (hence the name EMMA CASCADE). The load controlled by the EMMA unit (primary load) is ramped up first; the load controlled by the first extra SSR controller is ramped up next while the load on the PWM is brought back to zero and then ramped up again for excess power above the SSR load, and so on, in a seamlessly smooth continuous operation.
• All loads must be 3kW or less.
• The primary load (the one connected to the EMMA unit) must be equal to or less than the supply to the EMMA (i.e. if there is a 3kW supply to EMMA, the primary load must be 3kW or less). Secondary loads (those connected to the SSR controllers) must be equal to or less than the primary load.
• EMMA also eliminates flicker and ensures compliance with relevant harmonic current limits.

• The EMMA GVS (Grid Voltage Stabilization) unit allows the export current of 16amps under G83 while the rest is sent to heating. The EMMA GVS unit can be used to limit export and thereby overcome limitations imposed because of network capacity. This makes it possible to install large PV arrays and Wind Turbines in areas where it would not normally be possible.
• The GVS unit operates by governing the export current using clamp on CT's to monitor output from the Turbine or PV Array and the demand on the site coupled with monitoring of the grid voltage so that the voltage is kept within the G83 guidelines and prevents the inverters tripping out due to high voltage. This unit is specifically designed to prevent costly network upgrades and inverter outages.
• For sites where the DNO permits the export capacity of the machine or array then a normal SP15 CASCADE system or TP45 will suffice.

Also see our blog entry: How EMMA GVS Works.

EMMA GVS - Limiting the power exported to the grid

The Export Control EMMA GVS unit has the additional ability of limiting the amount of power exported to the grid to that permitted by the Network Operator. The export limit can be either a fixed maximum export current or an export current that varies with voltage within specified limits. EMMA GVS adjusts current exported to the grid by varying the load within the household as necessary. It also has the ability to isolate the micro-generator in the event of export current exceeding a specified maximum value/duration.

EMMA GVS - Power diverted to uses onsite

Typical limiting calculations are aimed at restricting exported current to 20 Amps when the system is at 253 volts and allowing this to increase proportionately to the maximum output of the renewable generator when the system is at 216.2 volts by diverting surplus power to a thermal store or other secondary devices - such as heating and cooling devices located on the same premises as the generator. The amount of power exported is kept to a minimum when surplus power is being diverted. The amount of power diverted is kept to a minimum when surplus power is being diverted. The amount of current exported is kept below the approved limits at all times.

EMMA GVS - Avoid network upgrade costs

On most remote sites considering micro-generators the network operators consider grid voltage regulation is the critical problem on most of the sites. They also say that EMMA GVS will save their customers typically €10k to €15k per installation when approved. They agreed that it is a much better and more sensible solution than upgrading the network.

EMMA GVS - Avoid surges for network operators

The really significant issue from the network owner/operator's point of view is the absence of diversity if large numbers of micro-generators are installed. It is normal to apply diversity factors of c.0.4 or less to normal loads when sizing distribution cables, transformers and switches because normal loads don't all switch on or off at the same time. This doesn't apply to sun and wind powered generators which ramp up and down simultaneously throughout local areas as gusts and clouds sweep by. Without EMMA these surges will are likely to cause significant problems. Standard EMMA just about eliminates this problem. EMMA GVS completely eliminates the problem.