ABB RELION REX640 Technical Manual page 424

Protection and control

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Protection functions

often encountered during the motor start-up and with abnormal conditions such as

locked rotor or unbalance, which both produce excess heat due to the skin effect.

The skin effect causes the current to distribute in a smaller surface in the rotor bars,

increasing the resistance, and therefore also the heating effect.

The function also provides locked rotor protection. The locked rotor condition can

be identified from the slip estimate that the function calculates.

Analog channel configuration

RPTTR has two analog group inputs which must be properly configured.

Table 485: Analog inputs

Operation principle

The function can be enabled and disabled with the

corresponding parameter values are "on" and "off".

The operation of RPTTR can be described using a module diagram. All the modules

in the diagram are explained in the next sections.

The function uses ambient temperature which can be measured locally or remotely.

Local measurement is done by the protection relay. Remote measurement uses

analog IEC 61850-8-1 GOOSE to connect AMB_TEMP input.

Figure 245: RPTTR module diagram

If the quality of remotely measured temperature is invalid or

communication channel fails the function uses ambient temperature set

Env temperature Set .

Three-phase currents

Three-phase voltages

Operation setting. The

Internal FLC

1MRS759142 F

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