July 2016
Application Note – Inverter AC Relay Control by Secondary
Protection Device
Introduction
In some cases, PV installations are required to have secondary grid protection that is independent of the inverter’s internal grid
protection (an example of secondary grid protection is defined in VDE-AR- N-4105). This secondary grid protection can be
provided by a device which controls two contactors connected in line with the grid and the inverter. It continuously monitors
grid parameters such as voltage and frequency and automatically disconnects the system from the grid if a parameter is outside
the permitted range by opening the contactors. Once the parameters are within the permitted range for the required time it
reconnects the system to the grid by closing the contactors.
Figure 1: Secondary Protection Device
Alternately, the inverter’s internal relays can be used instead of the external contactors. This option can save the cost of the
external contactors, which normally ranges between €100 and €1,000, depending on the installation size.
This application note describes how to connect such a device to the SolarEdge inverter and how to configure the relay control.
To use the AC Relay Control feature, the inverter communication board firmware (CPU) version must be 3.18xx and later.
For further related information about power control of SolarEdge inverters, please refer to:
Application Note Power Reduction Control
Application Note Power Control Options
Connecting a Secondary Protection Device to the SolarEdge Inverter
To control the inverter relays the secondary protection device is connected to the inverter’s Power Reduction Interface (PRI)
connector located on the inverter communication board. In an installation with a Control and Communication Gateway (CCG)
the device should be connected to the CCG’s PRI connector as shown in Figure 5. Only one of the four PRI signals (L1) is used to
control the internal inverter relays.
NOTE
Up to 15 inverters can be connected to a single secondary protection device. The total length for all inverters' cable wiring
cannot exceed 15 meters. For sites with more than 15 inverters, multiple devices should be used.
The secondary protection device should operate in a Normally Closed (NC) mode. In a normally closed circuit, power flows until
the relay is activated which disconnects the circuit and interrupts the power; the circuit is connected and the power returns
when the relay is deactivated.
1
CAUTION!
Relays typically have low IP protection and need to be placed inside an enclosure.
Figure 2: NC Relay Modes
NOTE
If RRCR power control is required, the default RRCR setting used by utilities for power reduction (L4/L3/L2/L1:
00010%, 0010 30%, 010060% and 1000 100%) must not be overridden.
Multiple Inverter System without RRCR
Connection procedure:
1
Connect two wires from the secondary protection device to the 5V and L1 PRI pins of any inverter (it does not have to be the
communication master inverter).
2
Connect wires from the L1 pin of one inverter to the L1 pin of the next inverter and so on.
3
Connect wires from the G pin of one inverter to the G pin of the next inverter and so on.
System behavior:
When L1=1, the inverter relays are closed
When L1=0, the inverter relays automatically open. They remain open until L1=1.
Figure 3: Multiple inverter system, no RRCR
2
Multiple Inverter System with RRCR
Connection procedure:
1
Connect a wire from the secondary protection device to the 5V of the inverter to which the RRCR is connected.
2
Connect a wire from the secondary protection device to the L1 of the first inverter to which the RRCR is connected.
3
Connect wires from the L1 pin of this inverter to the L1 pin of the next inverter and so on.
NOTE
The RRCR needs to be connected to the communication master inverter.
4
Connect wires from the G pin of one inverter to the G pin of the next inverter and so on.
System behavior:
Master inverter:
•
•
When L1 = L2 = L3 = L4 = 0 the inverter relays automatically open.
•
When L1=1 the inverter relays are closed. Any RRCR signals will be received from the master
inverter via RS485.
•
When L1=0 the inverter relays automatically open. They remain open until L1=1.
During any other signal combination, the inverter will behave according to the RRCR settings.
Slave inverters:
Figure 4: Multiple inverter system, with RCCR
3
Multiple Inverter System with RRCR and CCG
Connection procedure:
1
Connect one wire from the secondary protection device to the 5V PRI pin of the CCG.
2
Connect one wire from the secondary protection device to the L1 pin of the inverter connected to the CCG.
3
Connect wires from the L1 pin of this inverter to the L1 pin of the next inverter and so on.
4
Connect wires from the G pin of one inverter to the G pin of the next inverter and so on.
NOTE
The RRCR is connected to the CCG and not directly to an inverter. The secondary protection device is connected to
both the CCG and to the inverter to which the CCG is connected.
System behavior:
If L1=1, the inverter relays remain closed. Any RRCR power commands will be received from the CCG via RS485. If L1=0, the
inverter relays will automatically open. They will remain open until L1=1.
Figure 5: Multiple inverter system, with RRCR and CCG
4
Configuring AC Relay Control
Configuration Requirements
To use the AC Relay Control feature, the inverter communication board firmware (CPU) version must be 3.18xx and later.
For an upgrade file and instructions, contact SolarEdge support.
When AC Relay Control is enabled, all inverters in the system need to be configured to AC Relay Control mode.
If a CCG is installed, it should not be configured to AC Relay Control mode.
NOTE
AC Relay Control is disabled by default and should be enabled from the inverter menus.
Enabling AC Relay Control
System with RRCR
Select Communication Server <LAN>
Select Server <LAN>LAN
Select GPIO Conf.
> S e r v e r
< L A N >
L A N
C o n f
G P I O
C o n f
< R R C R >
Select Device Type < AC RELAY CTL+RRCR>.
> D e v i c e
T y p e
<
A C + R
>
System without RRCR
Select Communication Server <LAN>
Select Server <LAN>LAN
Select GPIO Conf.
Select Device Type AC RELAY CTL
> D e v i c e
T y p e
<
A C
>
Disabling AC Relay Control
Select Communication Server <LAN>
Select Server <LAN>LAN
Select GPIO Conf.
Select Device Type RRCR
5
Appendix - Three Relay RRCR and AC Relay Control
If the installation has a three relay RRCR, to use the AC Relay Control feature the system should be connected as follows:
Figure 6: Three Relay RRCR and AC Relay Control
The RRCR settings should be configured as follows:
Active Power
L1
L2
L3
L4
0%
1
1
0
0
30%
1
0
1
0
60%
1
0
0
1
100%
1
0
0
0
Relays Open
0
0
0
0
6
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