Siemens SINAMICS PERFECT HARMONY GH180 Function Manual page 201

The actual amount of time until the VFD trips can be taken directly from the figure.
Examples
• Example 1: Unit is running at 110% rating
I timeout = 1 second
Actual time to trip = 1 x 7.2 = 7.2 seconds
• Example 2: unit is running at 110% rating
I timeout = 50 second
Actual time to trip = 50 x 7.2 = 360 seconds
• Example 3: unit is running at 150% rating
I timeout = 60 second
Actual time to trip = 60 x 1 = 60 seconds
• Example 4: unit is running at 120% rating
I timeout = 60 second
Actual time to trip = 60 x 3.1 = 186 seconds
If a 150% overload is required for 1 minute and it is a variable torque load, Example 3 is the
recommended setup.
To use the table for other settings, the following equation can be applied:
where:
T
trip
I
timeout
T
I-overload
• A first alarm occurs when the T
• A second alarm occurs when the T
• Trip occurs when T
There is hysteresis on both alarms, but not on the fault.
Thermal Memory Retention
The system incorporates a feature that retains the thermal motor overload information in
nonvolatile memory so that if power is lost and then later restored, the same overload condition
can be applied as when the power was lost. The length of time the power is off is also considered
to adjust for motor cooling while the system was off.
NOTICE
Using Thermal Memory Retention
This feature only works in the "Straight Inverse Time" and "Inverse Time with Speed Derating"
modes.
NXGPro+ Control Manual
Operating Manual, A5E50491925A
= actual trip time
= menu trip time
= time to trip from table or figure at the overload amount used.
> T
ovld
T = I * T
trip timeout I-overload
> (0.75 * T
ovld Timeout
> (0.90 * T
ovld
resulting in a TOL fault.
Timeout
Operating the Control
7.7 Motor Thermal Overload Protection
).
).
Timeout
(0.1)
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