ABB RELION REX640 Technical Manual page 411

Protection and control

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1MRS759142 F

Improper analog channel configuration causes a validation error if the analog

channels are not completely configured or they do not match with certain settings.

For troubleshooting, check the contents of this chapter and also the preprocessing

blocks in this document. The configuration can be written to the protection relay

once the mismatch is corrected.

Operation principle

The function can be enabled and disabled with the

corresponding parameter values are "On" and "Off".

The operation of MPTTR 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 GOOSE to connect AMB_TEMP input.

Figure 238: Functional module diagram

Max current selector

Max current selector selects the highest measured TRMS phase current and reports

it to Thermal level calculator.

Internal FLC calculator

Full load current ( FLC) of the motor is defined by the manufacturer at an ambient

temperature of 40°C. Special considerations are required with an application where

the ambient temperature of a motor exceeds or remains below 40°C. A motor

operating at a higher temperature, even if at or below rated load, can subject the

motor windings to excessive temperature similar to that resulting from overload

operation at normal ambient temperature. The motor rating has to be appropriately

reduced for operation in such high ambient temperatures. Similarly, when the

ambient temperature is considerably lower than the nominal 40°C, the motor can

be slightly overloaded. For calculating thermal level it is better that the FLC values

Technical Manual

See the preprocessing function blocks in this document for the possible

signal sources.

If the quality of remotely measured temperature is invalid or

communication channel fails the function uses ambient temperature set

Env temperature Set .

Operation setting. The

Protection functions