Emerson Powerdrive F300 Reference Manual page 60
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Also See for Powerdrive F300:
- User manual (289 pages) ,
- Getting started manual (111 pages)
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Time for Motor Protection Accumulator to reach 100%
Assuming a single time constant model is being used (i.e. Motor Thermal Time Constant 2 Scaling (04.038), the time for
the Motor Protection Accumulator (04.019) to change from its initial value to 100% is given by the following equation:
Time to reach 100.0% = -τ1 x ln[(1 − C
C
represents the conditions that have persisted for long enough for the Motor Protection Accumulator (04.019) to reach a steady state value. If the
0
motor current and speed are I
C
= [(1 - K
) x (I
/ (K
x I
0
fe
0
1
Rated
C
represents the conditions that begin at the start of the time being calculated. If the motor current and speed are by I
1
C
= [(1 - K
) x (I
/ (K
x I
1
fe
1
1
Rated
Example 1: The effect of iron losses are not modelled (K
zero, Rated Current (05.007) ≤ Maximum Heavy Duty Rating (11.032) and the new level of current is 1.5 x Rated Current (05.007).
C
= 0
0
2
C
= [1.5 / (1.05 x 1.0)]
= 2.041
1
Time to reach 100.0% = -89 x ln(1 − 1/C
This is the default setting for Open-loop and RFC-A modes allowing an induction motor to run at 150% rated current for 60s from cold.
Example 2: The effect of iron losses are not modelled (K
(05.007), Rated Current (05.007) ≤ Maximum Heavy Duty Rating (11.032) and the new level of current is 1.5 x Rated Current (05.007).
2
C0 = [1.0 / (1.05 x 1.0)]
= 0.907
2
C1 = [1.5 / (1.05 x 1.0)]
= 2.041
Time to reach 100.0% = -89 x ln((1 − C1) / (C0 − C1)) = -89 x ln[(1 − 2.041) / (0.907 − 2.041)] = 7.6s
This is the default setting for Open-loop and RFC-A modes allowing an induction motor to run at 150% rated current for 7.6s after running under rated
conditions for a significant period of time.
Motor Protection Accumulator Reset
The initial value in the Motor Protection Accumulator (04.019) at power-up is defined by Motor Protection Accumulator Power-up Value (04.036) as
given in the table below.
60
) / (C
− C
)]
1
0
1
and w
then,
0
0
2
1.6
))
] + [K
x (w
/ w
)
]
fe
0
Rated
2
1.6
))
] + [K
x (w
/ w
)
]
fe
1
Rated
= 0), Motor Thermal Time Constant 1 (04.015) = 89s, the initial current is
fe
) = -89 x ln(1 − 1/2.041) = 60s
1
= 0), Motor Thermal Time Constant 1 (04.015) = 89s, the initial current is Rated Current
fe
and w
then,
1
1
Powerdrive F300 Parameter Reference Guide
Issue: 01.15.00
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