1-16 Product Overview
Parameter 75, Gnd Flt Inh Time, allows the installer to inhibit a
ground fault trip from occurring during the motor starting sequence
and is adjustable from 0…250 seconds.
Parameter 74, Gnd Flt Delay, allows the installer to define the time
period a ground fault condition must be present before a trip occurs. It
is adjustable from 0.1…25 seconds.
Parameter 73, Gnd Flt Level, allows the installer to define the ground
fault current at which the SMC-Flex will trip. It is adjustable from
1.0…5.0 A.
Important: The ground fault inhibit timer starts after the maximum
phase of load current transitions from 0 A to 30% of the
device’s minimum FLA Setting or the GF Current is
greater than or equal to 0.5 A. The SMC-Flex does not
begin monitoring for a ground fault condition until the
Gnd Flt Inh Time expires.
Ground Fault Alarm
The SMC-Flex will indicate a Ground Fault Alarm if:
• No warning currently exists
• Ground fault alarm is enabled
• GF Inhibit Time has expired
• GF Current is equal to or greater than the Gnd Flt A Lvl
Parameter 77, Gnd Flt A Lvl, allows the installer to define the ground
fault current at which the SMC-Flex will indicate a warning. It is
adjustable from 1.0…5.0 A.
Parameter 78, Gnd Flt A Dly, allows the installer to define the time
period a ground fault alarm condition must be present before a trip
occurs. It is adjustable from 0.1…25 seconds.
Thermistor/PTC Protection
The SMC-Flex provides terminals 23 and 24 for the connection of
positive temperature coefficient (PTC) thermistor sensors. PTC
sensors are commonly embedded in motor stator windings to monitor
the motor winding temperature. When the motor winding temperature
reaches the PTC sensor’s temperature rating, the PTC sensor’s
resistance transitions from a low to high value. Since PTC sensors
react to actual temperature, enhanced motor protection can be
provided to address such conditions as obstructed cooling and high
ambient temperatures.
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