One-Channel Connection To Drive Sto Terminals; General; Implementing The Reset Of The Safety Function; Indications Of The Safety Function - ABB ACS880-01 Application Manual

18 Implementing a motor thermal protection circuit

One-channel connection to drive STO terminals

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General

This section describes an implementation of the ATEX-compliant motor thermal protection
circuit:
• The circuit uses the ATEX-certified Safe disconnection function (option +Q971) of the
drive.
• There is a one-channel (non-redundant) connection of the motor protection relay to the
drive STO terminals. Both STO inputs of the drive are connected to same output contact
of the protection relay.
• One output contact of the protection relay is connected to a digital input of the drive.
• The drive shows an overtemperature indication when the digital input switches off (the
protection relay trips).
If you plan to use the one-channel (non-redundant) connection, make sure that you can
reach the necessary safety integrity level (SIL). According to EN 50495, SIL1 is sufficient
for the protection of category 2 and 3 equipment.
Note: The STO function of the drive must always have a redundant connection. See
Connection diagram (page
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Implementing the reset of the safety function

A manual reset is mandatory in the motor thermal protection function, if it is required for
ensuring the compliance of the system with Ex/ATEX regulations. After the motor thermal
protection function activates, the motor must not restart before a manual reset command is
given. You can implement a manual reset in the ATEX-compliant protection relay
(recommended). Use the reset button of the relay, or connect an external reset button to
the relay.
In this example, you can also configure a manual reset in the drive with the motor
overtemperature or STO indication parameters. See section
indications (page 25).
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Indications of the safety function

In this example, you can use the drive STO or the motor overtemperature indication. See
section Reset method and status indications (page
If you want to avoid parallel indications in overtemperature situations, you can set one or
several of the indication parameters value to No indication (or None) or Event:
•
the motor overtemperature indication with drive parameters 31.01...31.02 or
35.11...35.12
• the STO indication in the drive with drive parameter 31.22 STO indication run/stop
Make sure that at least one of these indications generates a fault if:
• the protection relay does not contain a manual reset, and
• the FSO module is not configured for an STO manual reset.
19).
Reset method and status
25).