This article introduces relay roles and product information focusing on inverters.
What is an inverter?
An inverter converts direct current (DC) produced by solar power generation to alternating current (AC) usable at home. Further, it is equipped with a convertor function to maintain solar-power-generated electricity at a constant voltage. While providing such functions, relays used for the DC side (for switching direct current loads) of the inverters are required to provide high capacity DC cutoff capabilities and high reliability since they are used as safety cutoff relays in the event of defects and failures of the batteries and power storage system. In addition, relays used for the AC side (for switching alternating current loads) of the inverters are required to provide high capacity AC cutoff capabilities and high reliability since they are used as safety cutoff relays for power grids to prevent abnormalities in consumer side circuits from impacting commercial power supply circuits. Next, let's check these applications in more detail.
Relay roles and product information
(1) AC side safety cutoff
Relays are used to safely shut down power grids. When an abnormal current is generated in an inverter, it is required to cut the current to prevent it from impacting the inverter’s power supply side. Iinverters are equipped with high capacity relays as part of safety measures to protect electric power grid systems.
(2) Standalone operations
During normal operations of an inverter, the contacts of the relay for standalone operations are in OFF state; however, the inverter is designed to turn the relay’s contacts ON to activate its standalone function in the event of a blackout due to a problem. Relays are used as safely measures and for standalone operations.
Recommended high capacity AC relays
＜HE-N relay＞
HE-N (1a 120 A) : A contact gap of 3.6 mm is secured.
＜HE PV relay＞
HE PV (1a 35 A, 48 A, 90 A 277 V AC) : A contact gap of 2.5 mm/3.0 mm is secured.
*Compact power relays capable of switching from 35 A to 90 A
＜HE-S relay＞
HE-S (2a/2a1b 35 A 277 V AC):Two-contact compact power relay with a secured contact gap of 3.2mm
＜LF-G relay＞
LF-G (1a 22 A, 33 A 250 V AC)：Compact power relays with a secured contact gap of 1.5 mm/1.8 mm
※Click the photograph of each product series to visit the website containing the corresponding detailed information.
▼ CAD/Catalog download
- Click here to download the HE-N relay data
- Click here to download the PV type HE relay data
- Click here to download the HE-S relay data
- Click here to download the LF-G relay data
Proposal for engineers!!
Simply incorporating one Panasonic 2a1b type HE-S relay in your system allows you to easily create safety cutoff and contact welding monitoring circuits as additional safety measures.
(One HE-S relay can check two lines, but two are required for circuits using 3-phase four lines.)
HE-S relay use case
* 2a1b type x 1 (use image)
<HE-S relay>
- Click here for detailed information.
- Click here to download the CAD and catalog data.
(3) Junction box (for DC cutoff)
A junction box can maintain the safety of a solar power generation system by cutting off DC lines in disasters such as fires. Additionally, the junction box can be remotely controlled during the maintenance of the solar panels, thereby reducing maintenance costs. For further safety measures, the box can cut off high currents in the event of abnormalities when it is connected to storage batteries (80 to 300 A types).
Recommended high capacity DC relays
<EP relay>
EP (1a 10 A to 300 A 1,000 V DC *）：High voltage cutoff relay. The capsule contact construction achieves high reliability.
* 1,000 V DC is the Max. switching voltage. The rating is 400 V DC.
※Click the photograph of each product series to visit the website containing the corresponding detailed information.
<EP relays>
- Click here to download the CAD and catalog data
Was it clear that high capacity relays are useful for designing each circuit to achieve the AC side safety cutoff, stand-alone operation, and DC side cutoff functions of an inverter?
This series of courses entitled ‘High capacity relays that support energy management’ has introduced the relay roles and product information that apply to each of the three products, namely the ‘Charging system,’ ‘Power storage system,’ and ‘Inverter.’
Panasonic offers high capacity relays that contribute to efficient energy management.
We would be happy if these articles help you deepen your understanding of relays and give you hints to solve problems when designing circuits.
* From a safety perspective, the use of our relay requires manufactures to confirm specifications and conduct evaluation test. Please understand that safety considerations prevent us from receiving inquiries from or dealing with private customers.
