32 ATEX-certified motor thermal protection function with Pt100 relays (+L514+Q971)
Operation principle
Without an FSO module
1. When the motor temperature rises, the sensor resistance increases linearly.
2. When the motor temperature exceeds the set operating temperature limit of the Pt100
relay, the relay indicates motor overtemperature through its output contacts.
3. The opening contacts of the extension relay(s) [-A81] ([-A82] and [-A83]) open the
STO circuit of the drive. This prevents the drive from generating the torque required to
rotate the motor.
4. The drive generates an STO indication (parameter 31.22, see page 44).
5. If the extension relay(s) [-A81] ([-A82] and [-A83]) are wired to a digital input, the loss
of the signal triggers a motor overtemperature fault in the drive (see page 44).
6. After the motor temperature has decreased to normal, the Pt100 relays reset
automatically.
7. The user must reset the drive faults either from the reset source defined by the user
(parameter 31.11, see page 45) or locally with the drive control panel:
• the STO fault in the drive (if configured with drive parameter 31.22, see page 44)
• the motor overtemperature fault in the drive (if configured, see page 44).
00 ACS880 ATEX cabinet.book Page 32 Tuesday, May 28, 2019 10:25 AM
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