Toshiba GR200 Series Instruction Manual page 302

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Thermal overload function (THM)

Apparatus such as cables, transformers, generators and others can become overheated when

overloaded beyond their respective design limits due to excessive demands being placed on the

system. The thermal overload function (THM) works by determining the temperature rise in

an item of primary equipment by monitoring the current in order to detect the thermal

overload of the apparatus.

THM has an exponential characteristics in accordance with the IEC 60255-149 standard.

THM determines both the

also determines the pre-load condition and signals a trip signal when an overload condition

THM issues a trip signal in accordance with an alarm stage that reflects the temperature

of the thermal overload condition. The alarm stage is configured using a setting; hence, the

user should determine the appropriate setting so that a trip signal can be issued before the

apparatus is overheated

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Several IED models do not have thermal overload features. To determine whether the

features are implemented in the IED or not, locate the IED ordering number; and check the

order number at "G&T position" referring to the comparison table below. For more information,

Appendix: Ordering

Table 2.18-1 Comparative table in respective ordering numbers

Thermal overload protection

✓: Applicable

loss and the cooling effect of the coolant simultaneously; THM

NA: Not applicable

6F2S1914 (0.49)

Ordering No. at "G&T"

GRL200 (Soft 033 & 037)

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