Modular inverters can scale for renewable energy

Modular DC/AC inverters by Cotek Systems in the SR-1600-Plus series are suitable for industrial, telecomms and datacomms applications, renewable energy as part of rackmount systems or as standalone units. They are available from Relec Electronics.

They feature Modbus communication, in addition to simple network management protocol (SNMP). The RS-485 Modbus port allows users to control and monitor parameters, such as voltage, output power, internal temperature and protection levels. The 1600VA inverter modules are for either 24V or 48V inputs and the series includes a bespoke 2U sub-rack, a system controller, and options for remote control and maintenance bypass switches.

The inverters have 89 to 91% efficiency in DC/AC mode and provide line conditioning of the AC input supply for use with modern IT systems where the incoming primary AC supply can be variable or non-sinusoidal, for example from a generator. The power factor is above 0.99 and maximum AC efficiency is 95%.

The inverters can be used as a DC/AC inverter, where the input source is a DC or battery supply, and also as AC mode with DC back up with zero transfer time. They can also power share between the AC and DC sources.

There is a wide range of AC inputs (minimum ±20%) and provides a regulated, adjustable AC output (±2%). For renewable energy applications, the inverters can also split the load between the AC and DC input source, where DC supply is not available all the time, or to take advantage of low tariff AC sources.

The inverters are designed for use with a bespoke 2U sub-rack or can be used as standalone units. Blanking panels support unpopulated slots, for future expansion. Sub-racks can be supplied with the SN-1 Plus interface for Ethernet support, or CR-21 for programming at a local level. The SR-2U2-Plus sub-rack can accommodate up to four SR-1600-Plus modules, providing 1600 – 6400VA outputs, with options for redundancy and upgrades.

The system is scalable with up to eight sub-racks, or 32 modules connected in parallel capable of supplying up to 51.2kVA. Each DC/AC inverter has a footprint of just 105 x 83 x 405mm and are hot swappable in live systems for uninterrupted operation in sensitive systems during maintenance and system upgrades.