Siemens SINAMICS G120 Operating Instructions Manual page 301

1. The minimum monitoring speed tolerance p9691 should be set to
2. The resulting frequency tolerance ∆Fhigh due to the minimum frequency tolerance at high
3. The resulting frequency tolerance ∆ Flow due to the minimum frequency tolerance at low
4. The valid delay ∆F
5. Finally the minimum braking ramp delay can be calculated as
The safe frequency envelope results from a time delay (p9680) in t-direction and an
additional frequency tolerance ∆F (caused by measurement inaccuracies) and ∆F
by slipcompensation) in F-direction.
Fault reaction time
An LSTO is always triggered immediately after the parameterised safe envelope frequency is
exceeded. However, note that the actual frequency may deviate (is usually higher) from the
set point frequency due to normal operating states (slip compensation, PID, etc.) or internal
drive faults.
Therefore, as the envelope starting frequency is related to the actual frequency the
parameterised envelope may be shifted as show in the next figure.
Control Units CU240S
Operating Instructions, 11/2006, A5E00766042B AA
P9691 ≥ 1.15 ∙ P9690 + ∆F
thus defining the minimum frequency tolerance as
∆F = P9691 - P9690 - ∆F
Where ∆F is given as
slip
∆F = P0330∙ r0310 / 100%
slip
This prevents sporadic trips caused by measurement inaccuracies and additional slip
compensation. Note that according to the above formula, P9691 must be set, even if SLS
is not parameterised.
frequencies is then given as
∆F ≥ 0.15 ∙ F - ∆F
high max
where Fmax defines the maximum process frequency at initiation of SLS or SS1.
frequencies is then given as
where the gradient m is defined as
The denominator D in the above formula is calculated as follows:
SLS parameterised:
SS1 parameterised:
SLS and SS1 parameterised:
delay
∆F = max [∆F , ∆F
delay low
slip
slip
D = 2 ∙ P9690
D = 2 ∙ P9682
D = 2 ∙ min [P9682, P9690]
is then given as maximum of
]
high
Functions
8.18 Fail-safe functions
(caused
slip
8-105