Tigo's Pure Signal Transmitter allows multiple PLC transmitters to be linked together to provide a single, synchronized keep-alive signal to large arrays. This allows greater protection from signal interference (also known as crosstalk).
Crosstalk is an electromagnetic phenomenon that can cause interference between two independent signal transmission sources (wires or antennas) that are in close physical proximity to each other. Crosstalk can affect a wide variety of products, and is not limited to photovoltaic systems.
This article provides installation required practices to mitigate crosstalk when using multiple RSS Transmitters (or transmitter groups).
Wiring for Pure Signal Technology
Pure Signal RSS Transmitters communicate through a (series or daisy-chain) wired connection.
The first transmitter (RSSx Leader) communicates to the next in series (Follower), until the last transmitter has received the signal.
This arrangement synchronizes the signal so every PV conductor in the conduit, raceway or cable tray is operating on the same pulse (without phasing issues), which reduces the likelihood of crosstalk.
Important: When installing the Commercial RSS Transmitter with Pure Signal Technology, synchronized groups of transmitters should all be powered from the same power supply, for a consistent signal.
Separation of RSS Transmitters onto different power supplies creates 2 groups, offsetting the RSS Pulse. This can lead to phasing, distortion or outright cancellation of the signal(s).
For complete installation instructions refer to the Quick Start Guide
Design and Installation Requirements
To maintain signal integrity in a PLC system, required practices and product specifications must be adhered to. The following practices are required in a Tigo rapid shutdown system using power line communication.
The RSS Transmitter can accommodate a string with a maximum round-trip distance (from positive to negative) of 300 m / 985 ft. If the longest string in a system exceeds 300m (and is less than 500m), two cores may be used in series on the string to amplify the signal. Tigo Sales Engineering must approve this type of design.
Up to a maximum of 10 RSS Transmitters with Pure Signal Technology can be connected to make a single Pure Signal. If the system is very large (over 10 Pure Signal RSS Transmitters), it will require more than one group of RSS Transmitters. Since these groups will have different signals, they must be treated as having Crosstalk potential, and steps must be taken to separate the signals.
The total length of the daisy-chained communication wiring connecting all the RSS Transmitters in a single Pure Signal technology group must not exceed 100ft (30m).
Positive/negative home run string conductors from the same the Pure Signal group should be arranged together in one conduit.
Never separate the + and – of the same string.
Maintain greater than 8 inches (20cm) distance between conduits served by different Pure Signal groups and conductors of different systems.
Never run +/- string conductors from different Pure Signal groups in the same conduit or within 20cm.
Never place conductors from different Pure Signal groups or from different systems together in the same cable tray. Open cable trays provide no additional protection from crosstalk.