GE Multilin 850 Instruction Manual page 425

Feeder protection system

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CHAPTER 4: SETPOINTS

850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL

RTD type copper (Cu) is only available when order code option 'S' is chosen for Slot B or C.

RTD Protection

The 850 relay can monitor up to 13 RTDs, each of which can be configured to have a trip

temperature and an alarm temperature. The RTD Temperature protection menu will be

seen on the relay upon availability of RTD input/inputs. The minimum RTD Temperature

requirement for the user is to set the setpoint "Type". The default value for "Type", for each

RTD is "100 Ω Platinum". The protection RTD Trip, and RTD Alarm from the menu are

optional. They respond to directly measured RTD temperature. The Alarm temperature is

set slightly above the normal measured temperature for the transformer top-oil, bottom-

oil, or LTC oil. The Trip temperature is normally set at the maximum permissible oil

temperatures defined as dangerous for the transformer and the transformer insulation.

This element also monitors the RTD broken connection and blocks the RTD trip and alarm

functions if the RTD connection is detected as Open or Shorted and generates RTD Open

and RTD Shorted FlexLogic operands. An RTD is detected as Open when the RTD

connection is either open or the temperature is greater than 250°C. An RTD is detected as

Shorted when the RTD connection is either shorted or the temperature is equal to less than

RESISTANCE (IN OHMS)

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