Reduced Voltage Starting - GE MI-869 Instruction Manual

CONTROL

Reduced Voltage Starting

NOTE:
4–330
The 869 can control the transition of a reduced voltage starter from reduced to full voltage.
That transition may be based on "Current Only", "Current and Timer", or "Current or Timer"
(whichever comes first). When the 869 detects a 'Motor Starting' condition the current will
typically rise quickly to a value in excess of FLA (e.g., 5 × FLA). At this point, the Start Timer
is initialized while the motor current is simultaneously monitored. When the transition from
reduced to full voltage is initiated, the Reduced Volt Ctrl operand will be asserted for 1
second. The intention is to link this operand to the auxiliary output relay that can control
reduced voltage start contactors. The feature can also assert a trip signal if the current or
timer transitions do not occur as expected. This element is functional only if the external
motor Start/Stop command is used. An example of the control wiring related to this
element is depicted in the diagram, Reduced Voltage Start Control Circuit. A typical current
– time diagram of a reduced voltage start sequence is shown in the diagram, Reduced
Voltage Start Current Characteristic.
Figure 4-133: Reduced Voltage Start Contactor Control Circuit
Figure 4-134: Reduced Voltage Start Current Characteristic
If this feature is used, the Starter Status Switch input must be either from a common
control contact or a parallel combination of Auxiliary '52a' contacts or a 1series
combination of Auxiliary '52b' contacts from the reduced voltage contactor and the full
voltage contactor as shown in the diagram, Reduced Voltage Starting wiring example.
869 MOTOR PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 4: SETPOINTS