This article introduces the new RSS Transmitter with Pure Signal technology!
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The RSS Transmitter with Pure Signal technology is a patented Tigo innovation that allows multiple transmitters to be connected together and act as one harmonious 'keep alive' signal for all MLPEs (TS4-A-Fs/TS4-A-2Fs) on a system.
Benefits are:
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Frequently Asked Questions (FAQ):
Below, you will find some of the most frequently asked questions regarding the installation and usage of the RSS Transmitter and the RSS Transmitter with Pure Signal. Click on one of the questions (below) to go to the answer.
General:
- What is Pure Signal technology?
- How do you tell the difference between the two RSS Transmitters?
- How do you connect the RSS transmitters with Pure Signal Technology?
- What is the rating of the power supply for the RSS Transmitter?
- Why are there two terminals at the bottom of the RSS Transmitters?
- What is the purpose of the Core?
- Why do the Cores have different colors on either side?
- Are there inverters that already have the RSS Transmitter integrated?
Design:
- What documentation / training resources are available for the RSS Transmitter with PST?
- What are the top 3 design criteria that can help to reduce the need for assistance?
- Can I replace an existing RSS Transmitter with the Pure Signal model?
- When should you use the RSS Transmitter, versus the RSS Transmitter with PST?
- Can you mix the RSS and Pure Signal Transmitters within one system?
- What happens if a wire is connected to the third terminal on the RSS Transmitter?
- Should the Positive or Negative home run be passed through the Core?
- Are there any distance restrictions for the RSS Transmitters?
- What if the PV array home runs exceed 1640 feet (500 meters)?
- How many PV array home runs can fit inside the Core?
- What if the inverter has more than 10 Maximum Power Point Trackers (MPPT) or strings?
- What are some things the designer can do to reduce the chances of crosstalk?
- Do I need to separate conductors if I use cable trays in my commercial projects?
- If I use the Pure Signal RSS Transmitter, do I need to consider crosstalk?
Troubleshooting:
Q: What is Pure Signal technology?
A: Pure Signal technology (PST) allows the Tigo RSS Transmitter to act independently, or in coordination with other PST transmitters, to provide one common (or aligned) signal over a large system. This increases the ease of installation and reduces conductor crosstalk concerns.
Q: How do you tell the difference between the two RSS Transmitters?
A: Although the transmitters share a similar form factor (and use the same transducer Cores), there are some subtle but important differences:
Both transmitters can be used with the TS4-F and -2F products and use power line communication to transmit the keep-alive signal. However, the Pure Signal RSS Transmitter is able to sync its keep-alive signal with up to 10 transmitters. This feature reduces the chances of crosstalk within this RSS Transmitter system.
Q: How do you connect the RSS transmitters with Pure Signal Technology?
A: Pure Signal technology requires multiple transmitters to be connected using a Leader-Follower method. For more information, see: Quick Start Guide: RSS Transmitter with Pure Signal technology
Q: What is the rating of the power supply for the RSS Transmitter?
A: Both the RSS Transmitter and RSS Transmitter with PST require a 12V DC input. Tigo offers a power supply (either separately or in a kit) that includes all the necessary components inside a NEMA 3R enclosure. The power supply must be fed by either 120V (residential) or 277V (commercial) on the AC side of the power supply (bottom).
The top of the power supply is the DC output to the RSS Transmitter. Wire the output of the power as shown. Do not use the third terminal on the top of the RSS Transmitter. It is a vestigial feature that will permanently put the system into rapid shutdown mode if connected.
Notice the ground wire that is also inserted into the negative terminal of the power supply. This is deliberate, and a small ferrule is included in the kit. Crimp the ground and negative wire and insert into the negative terminal.
Q: Why are there two terminals at the bottom of the RSS Transmitters?
A: These terminals accept the connectors for either one or two Cores.
The terminals are color-coded, black and white, and the corresponding ferrules of the Core wires must connect to the same Transmitter terminals.
Q: What is the purpose of the Core?
A: The Core is a current transformer (CT) that is connected to the bottom of the RSS Transmitter. This CT is used to induce the keep alive signal onto the PV array home runs that pass through it.
The Transmitter creates the keep alive signal and sends it to the Core.
The Transmitter can accept one or two Cores.
Q: Why do the Cores have different colors on either side?
A: The Core has a black side and a white side used to properly orient the Core to the PV array and Inverter.
The black side should always face the PV array, and the white side should always face the PV inverter.
Q: Are there inverters that already have the RSS Transmitter integrated?
A: Yes, there are many options for inverters with integrated RSS Transmitters. Select either link (below) to see the full list:
At this time, both options only offer the RSS Transmitter (without PST).
Q: What documentation / training resources are available for the RSS Transmitter with Pure Signal Technology?
Tigo provides a robust platform with several resources for you to learn more about our products:
Q: What are the top 3 design criteria that can help to reduce the need for assistance?
A: When using either model of RSS Transmitter, the design must eliminate the potential of crosstalk at all costs. This is the first line of defense.
- Ensure separation of Transmitters
Separate conductors from different RSS Transmitters or groups of Pure Signal Transmitters by at least 8 inches. Do not run them in the same conduit. These signals are not synchronized, and if the conductors are too close, they will interfere with each other and cause abnormal TS4-A-F/-2F operation.
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Ensure the basic Core criteria are met.
Only run the negative conductors through the RSS Transmitter Core. Running both sets will cancel the signal and result in abnormal system behavior. Limit the maximum number of conductors through the Core to 10.
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Ensure RSS Transmitter wiring is correct
- Ensure the 12V power supply is wired properly on the AC side (towards the grid) and the DC side (towards the Transmitter)
- Ensure Pure Signal Transmitter wiring is connected properly.
- When wiring the RSS Transmitter (non-Pure Signal), do not connect a wire in the furthest right terminal on the top of the transmitter.
RSS Transmitter (non pure signal)
Orient the black side of the Core towards the PV Array
Q: Can I replace an existing RSS Transmitter with the Pure Signal model?
A: Yes. Also, see the question on mixing RSS and Pure Signal Transmitters below.
Q: When should you use the RSS Transmitter, versus the RSS Transmitter with Pure Signal Technology?
A: If the project requires only a single inverter (typically residential), then Tigo recommends the RSS Transmitter (without PST).
If the project is a commercial application, it may have multiple inverters. For these, Tigo recommends the RSS Transmitters with Pure Signal Technology (PST).
Q: Can you mix the RSS and Pure Signal Transmitters within one system?
A: The mixing of transmitters (with and without PST) within a system is not advised, as it involves secondary signal management. However, if you are working on a system that has mixed RSS transmitters, it is important to:
- Wire all transmitters that have RSS Transmitters PST using the Leader-Follower method. Refer to step 2.2 of the Quick Start Guide: RSS Transmitter with Pure Signal technology.
- Follow the 'PV Conductor Installation – Multi Transmitter Systems – Required Practices' for all conductors that include either a non-PST RSS Transmitter or a mix of PST and non-PST RSS Transmitters. These required practices are in the Installation Manual - TS4-F, TS4-A-F, TS4-A-2F (Fire Safety), RSS Transmitter.
Also, see Crosstalk and How to Mitigate it, to avoid potential issues in your design.
Q: What happens if a wire is connected to the third terminal on the RSS Transmitter?
A: The Transmitter will be locked into rapid shutdown mode if any wire is connected to the third terminal (farthest right).
A solid red LED will appear on the bottom of the Transmitter.
Q: Should the Positive or Negative home run be passed through the Core?
A: Always run the negative conductors through the Core.
Q: Are there any distance restrictions for the RSS Transmitters?
A: Yes! Since the keep alive signal must travel from the negative home runs through the array and back, two distance criteria must be met.
For a single Core, the round trip distance is 1000 feet (300 meters).
If the roundtrip distance is greater than 1000 feet, use two Cores. This extends the round trip distance to 1640 feet (500 meters).
Q: What if the PV array home runs exceed 1640 feet (500 meters)?
A: If the home runs exceed 1640 feet, the keep alive signal will not be strong enough to reach the TS4-F/-2F on the end of the strings. This can result in abnormal operation and possible damage to the units.
The solution is to relocate the inverter so that the homerun distance stays within the Tigo design criteria.
Q: How many PV array home runs can fit inside the Core?
A: A maximum of 10 conductors may fit inside a Core from a single inverter. If there are more conductors inside the Core, then the keep-alive signal strength may not be strong enough to penetrate the outer conductors and reach the ones in the middle of the bundle.
Poor signal strength may cause abnormal TS4-F/-2F operation.
Q: What if the inverter has more than 10 Maximum Power Point Trackers (MPPT) or strings?
A: For commercial applications, it is common for these larger inverters to have more than ten string inputs. In this case, split the strings between an RSS Transmitter using two Cores.
Q: What are some things the designer can do to reduce the chances of crosstalk?
A: The most important thing to consider is keeping separate transmitter PV conductors away from each other.
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RSS Transmitter
Separate PV homeruns from multiple inverters.
- Do not run conductors from separate inverters in the same conduit. The Transmitters are not synced and will introduce crosstalk, resulting in abnormal system behavior.
Maintain at least 8 inches of separation between conductors of different Transmitters of different PV inverters.
Always keep the positive and negative conductors from the same string in the same conduit.
Q: Do I need to separate conductors if I use cable trays in my commercial projects?
A: Yes! You must maintain at least 8 inches of separation between conductors of different RSS Transmitters (i.e., inverters), even in cable trays.
Also, when using cable trays, twist the positive and negative conductors of the same string. This will reduce the chances of crosstalk.
Q: If I use the Pure Signal RSS Transmitter, do I need to consider the design requirements to reduce crosstalk?
A: It depends! Since the Pure Signal Transmitters sync their keep-alive signals, many crosstalk concerns are eliminated. However, commercial designs using many PV inverters may need to consider crosstalk mitigation strategies.
For example, suppose the system uses more than 10 Pure Signal RSS Transmitters. In that case, you must separate those Transmitter subsystems from each other so that they do not introduce crosstalk in the other subsystems.
Q: What do the blink patterns on the RSS PST Transmitter mean?
A: The Leader will display a solid red LED during normal operation. It will also display a blinking green LED when all Follower Transmitters are connected and receiving the sync signal.
Followers will only show a blinking green LED when they receive the sync signal from the Leader.