Schweitzer Engineering Laboratories SEL-701, Инструкция по эксплуатации

Страница: 98 / 468

701 Motor Protection Relay
Date Code 20010719
Settings Calculation
RTD-Based Protection
4.34
The SEL-701 Relay provides temperature alarms and trips using the RTD
temperature measurements and the alarm and trip temperature settings in Table 4.25 .
The temperature setting range is dependent on the Temperature Preference setting so
you can enter your alarm and trip temperatures in degrees Celsius or degrees
Fahrenheit.
The relay issues a winding temperature alarm if any of the healthy winding RTDs
(RTD Location setting equals WDG) indicate a temperature greater than its RTD
Alarm Temperature setting. The relay issues a winding temperature trip if one or two of
the healthy winding RTDs indicate a temperature greater than their RTD Trip
Temperature settings. Two winding RTDs must indicate excessive temperature when
the Enable Winding Trip Voting setting equals Y. Only one excessive temperature
indication is required if Winding Trip Voting is not enabled. Bearing Trip Voting works
similarly.
The alarm and trip temperature settings for Bearing, Ambient, and Other RTD
types function similarly except that trip voting is not available for Ambient and Other
RTDs.
To disable any of the temperature alarm or trip functions, set the appropriate
temperature setting to OFF.
Only healthy RTDs can contribute temperatures to the alarm and trip functions.
The relay includes specific logic to indicate if RTD, leads are shorted or open.
When you have connected an ambient temperature sensing RTD and set trip
temperatures for one or more winding RTDs, the relay gives you the option to enable
RTD thermal model biasing. When you enable RTD biasing, the relay:
Calculates RTD % Thermal Capacity and adds the value to the
Thermal Meter values.
Automatically reduces the winding RTD trip temperatures and
thermal element trip threshold if ambient temperature rises above
40°C.
Provides an RTD Bias Alarm if the winding temperature exceeds
60°C rise over ambient and the RTD % Thermal Capacity exceeds the
thermal element % Thermal Capacity by more than 10%.
The relay calculates RTD % Thermal Capacity using Equation 4.4 :
Equation 4.4
RTD%
Thermal Capacity
Winding RTD
Temperature
Ambient
Temperature
è ø
æ ö
–
Winding RTD Trip
Temperature
Ambient
Temperature
è ø
æ ö
–
----------------------------------------------------------------------------------------
100%
•
=