Hitachi L2002 energized, AL0 AL1 AL2, AL0 AL1 AL2, AL0 AL1 AL2, de-energized, Internal Relay Output, Operations and Monitoring

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Using Intelligent Output Terminals

Internal Relay Output

The inverter has an internal relay output with normally open and normally closed contacts (Type 1 form C). The output signal that controls the relay is configurable; the Alarm Signal is the default setting. Thus, the terminals are labeled [AL0], [AL1], [AL2], as shown to the right. However, you can assign any one of the nine intelligent outputs to the relay. For wiring purposes, the general terminal function are:

•[AL0] – Common contact

•[AL1] – Normally open contact

•[AL2] – Normally closed contact

Inverter logic circuit board

AL0 AL1 AL2

The relay itself can be configured as “normally open or closed.” Parameter C036, Alarm Relay Active State, is the setting. This setting determines whether or not the relay coil is energized when its output signal is OFF:

•C036=00 – “Normally open” (relay coil is de-energizedwhen output signal is OFF)

•C036=01 – “Normally closed” (relay coil is energized when the output signal is OFF)

Operations and Monitoring

Since the relay already has normally open [AL1] and normally closed [AL2] contacts, the purpose of the ability to invert the relay coil’s active state may not be obvious. It allows you to determine whether or not an inverter power loss causes the relay to change state. The default relay configuration is the Alarm Signal (C026=05), as shown to the right. And, C036=01 sets the relay to “normally closed” (relay coil normally energized). The reason for this is that a typical system design will require an inverter power loss to assert an alarm signal to external devices.

The relay can be used for other intelligent output signals, such as the Run Signal (set C026=00). For these remaining output signal types, the relay coil typically must NOT change state upon inverter power loss (set C036=00). The figure to the right shows the relay settings for the Run Signal output.

If you assign the relay an output signal other than the Alarm Signal, the inverter can still have an Alarm Signal output. In this case, you can assign it to either terminal [11] or [12], providing an open collector output.