Table 4.30 Underpower Element Settings - Schweitzer Engineering Laboratories SEL-701 Instruction Manual

When you apply the SEL-701 Relay on a synchronous motor, the VAR Element
Arming Delay disarms the reactive power elements for a settable time after the motor
starts. This allows the motor to be brought to full speed and the field applied. After the
VAR Element Arming Delay expires, the VAR Alarm and VAR Trip elements are
enabled. If the positive or negative reactive power exceeds the appropriate threshold for
longer than the time delay setting, the relay can issue an alarm or trip signal. The
reactive power elements are disabled when the motor is stopped or starting. These
elements can be used to detect synchronous motor out-of-step or loss-of-field
conditions.
Refer to Figure 8.1 on page 8.6 in Section 8: Metering & Monitoring
power measurement convention.
For application on an induction motor, disable the elements by setting both the
Negative VAR Alarm Pickup and Negative VAR Trip Pickup settings to OFF.
Underpower Elements
Table 4.30 Underpower Element Settings
Table 4.30 Underpower Element Settings
Setting Prompt
Phase Underpower Alarm Pickup
Phase Underpower Alarm Time Delay
Phase Underpower Trip Pickup
Phase Underpower Trip Time Delay
Underpower Element Arming Delay
a
Setting range shown for ITAP = 5 A. Range is 6–400 W when ITAP = 1 A.
The SEL-701 Relay Underpower Element Arming Delay disarms the underpower
elements for a settable time after the motor starts. This allows the motor to be brought
to full load. After the Underpower Element Arming Delay expires, the Phase Under-
power Alarm and Phase Underpower Trip elements are enabled. If the real three-phase
power falls below the alarm or trip threshold for longer than the time delay setting, the
relay can issue an alarm or trip signal. The underpower elements are disabled when the
motor is stopped or starting. These elements operate in addition to the Load Loss func-
tion and you can use them to detect motor load loss and other underpower conditions.
Disable the elements by setting both the Phase Underpower Alarm Pickup and
Phase Underpower Trip Pickup settings to OFF.
Date Code 20010719
Voltage-Based Protection (Relay Models 0701001X & 0701011X)
Setting Range
OFF, 30–2000 W
0.00–400.00 s
OFF, 30–2000 W
0.00–400.00 s
0–15000 s
Settings Calculation
for the relay
Setting Name =
Factory Default
a
37PAP = OFF
37PAD = 0.00
a
37PTP = OFF
37PTD = 0.00
37DLY = 10
701 Motor Protection Relay
4.39