Siemens SINAMICS PERFECT HARMONY GH180 - Page 201

The actual amount of time until the VFD trips can be taken directly from the 󹪝gure.
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:
T
trip
= I
timeout
* T
I-overload
(0.1)
where:
T
trip
= actual trip time
I
timeout
= menu trip time
T
I-overload
= time to trip from table or 󹪝gure at the overload amount used.
• A 󹪝rst alarm occurs when the T
ovld
> (0.75 * T
Timeout
).
• A second alarm occurs when the T
ovld
> (0.90 * T
Timeout
).
• Trip occurs when T
ovld
> T
Timeout
resulting in a TOL fault.
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 o󹪜 is also considered
to adjust for motor cooling while the system was o󹪜.
NOTICE
Using Thermal Memory Retention
This feature only works in the "Straight Inverse Time" and "Inverse Time with Speed Derating"
modes.
Operating the Control
7.7 Motor Thermal Overload Protection
NXGPro+ Control Manual
Operating Manual, A5E50491925A 199