Time Between Starts - GE MI-869 Instruction Manual

CHAPTER 4: SETPOINTS

Time Between Starts

869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
EVENTS
Range: Disabled, Enabled
Default: Enabled
TARGETS
Range: Disabled, Self-reset, Latched
Default: Latched
Figure 4-130: Maximum Starting Rate logic diagram
The Time Between Starts function enforces a configurable minimum time duration
between two successive start attempts. A time delay is initiated with every start attempt,
and a new start is not allowed until the specified interval has lapsed. The timer feature is
useful in enforcing the duty limits of starting resistors or starting autotransformers.
At the detection of the motor start, the Time Between Starts timer is loaded with the
entered Minimum Time. Even unsuccessful start attempts are logged as starts for this
feature. Once the motor is stopped, if the time elapsed since the most recent start is less
than the Minimum Time setting, the Start Inhibit operand is activated to block the motor
start. If a block occurs, the lockout time is equal to the time elapsed since the most recent
start subtracted from the Minimum Time setting.
Example: If Minimum Time is programmed as 25 min.
• A start occurs at T = 0 minutes
• The motor is stopped at T = 12 minutes
• A block occurs. The lockout time is 25 minutes – 12 minutes = 13 minutes
If the Emergency Restart input is asserted while the motor is stopped or tripped during a
Time Between Starts lockout, the Time Between Starts timer is reset. This causes a dropout
of the Start Inhibit operand and allows a new start. If the motor starts while the Emergency
Restart input is asserted, the lockout timer does not remain reset and starts running from
the rising edge of the Motor Starting state. However, Start Inhibit and Time Btwn Start OP
will remain reset until Emergency Restart Input is de-asserted.
The status of the Time Between Starts element (including the time) is stored into a non-
volatile memory and remains in the memory after the power is removed from the 869.
When the power is restored, the Time Between Starts element continues working normally
using the information collected before the power loss if the real time clock worked properly
during the power loss. However, when the relay power is restored and if the clock is not
CONTROL
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