DEMA CPM 311, User Manual

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Custom Protection Curves
CPM 311 Special Curves include inverse protection curves for electromechanical relays, constant time
characteristic and reset curves. These curves are listed below.
1. SA Semic: Semiconductor Protection Curve.
2. SB DI: Definite Inverse Curve.
3. SC CO2: Short time Inverse Curve.
4. SD CO8: Long Time Inverse Curve.
5. SE CO-C3H: Standard Inverse Curve.
𝒕 = [
𝑨
(
𝑰
𝑰
𝑺
)
𝜶
− 𝟏
+ 𝑩] × 𝑻𝑴𝑺
Universal trip time delay formula is given above, while special curve parameters are given on the
below table.
t
Trip delay (s).
A A constant for the characteristic (s).
I Momentary current (A).
Is Set current threshold (A).
α A constant for the characteristic (-).
B A constant for the characteristic (s).
TMS Time Multiplier Setting (-).
↺
Curve Type Trip Delay Formula Reset Delay Setting
Zone
SA Semic
Semiconductor Protection
𝒕 =
[
𝟑𝟓𝟓𝟎𝟎 𝒔
(
𝑰
𝑰
𝑺
)
𝟔
− 𝟏]
× 𝑻𝑴𝑺
𝑫𝑴𝑻 (𝟎. 𝟎𝟒 − 𝟏𝟎𝟎) 𝒔
SB DI
Definite Inverse
𝒕 =
[
𝟐. 𝟗𝟔𝟖𝟕𝟓 𝒔
(
𝑰
𝑰
𝑺
)
𝟐.𝟑
− 𝟏
+ 𝟏. 𝟗𝟔𝟖𝟕𝟓 𝒔
]
× 𝑻𝑴𝑺
𝑫𝑴𝑻 (𝟎. 𝟎𝟒 − 𝟏𝟎𝟎) 𝒔
SC CO2
Short Time Inverse
𝒕 =
[
𝟎. 𝟎𝟎𝟗𝟐 𝒔
(
𝑰
𝑰
𝑺
)
𝟎.𝟎𝟐
− 𝟏
+ 𝟎. 𝟎𝟎𝟖 𝒔
]
× 𝑻𝑴𝑺
𝑫𝑴𝑻 (𝟎. 𝟎𝟒 − 𝟏𝟎𝟎) 𝒔
or
𝑹𝑻𝑴𝑺 (𝟎. 𝟎𝟐𝟓 − 𝟑. 𝟐)
SD CO8
Long Time Inverse
𝒕 =
[
𝟐𝟏 𝒔
(
𝑰
𝑰
𝑺
)
𝟐
− 𝟏
+ 𝟎. 𝟕𝟐𝟎 𝒔
]
× 𝑻𝑴𝑺
𝑫𝑴𝑻 (𝟎. 𝟎𝟒 − 𝟏𝟎𝟎) 𝒔
or
𝑹𝑻𝑴𝑺 (𝟎. 𝟎𝟐𝟓 − 𝟑. 𝟐)
SE CO-C3H
Standard Inverse
𝒕 =
[
𝟏. 𝟖𝟏 𝒔
(
𝑰
𝑰
𝑺
)
𝟏.𝟎𝟓
− 𝟏
+ 𝟎. 𝟔𝟖𝟎 𝒔
]
× 𝑻𝑴𝑺
𝑫𝑴𝑻 (𝟎. 𝟎𝟒 − 𝟏𝟎𝟎) 𝒔
or
𝑹𝑻𝑴𝑺 (𝟎. 𝟎𝟐𝟓 − 𝟑. 𝟐)