119 • Start Procedure for Medium voltage Motor
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In the MPS-3000 SYSTEM PARAMETER setting page, please set:
LINE VOLTS = Actual rated line voltage (should be equal or lower than starter rated voltage).
VT PRIMARY = Starter rated voltage (the Electronic Potential Transformer is calibrated to
the starter rated voltage).
VT SECONDARY = 120 (the EPT “secondary” rated voltage).
MOTOR FLC = Actual Motor Name Plate (Rated) current (should be equal or lower than
starter rated current).
CT PRIMARY = 2.5 x Starter Rated Current. (See note 1 below)
GND CT PRIMARY = same as CT PRIMARY setting.
In the DPM-10 PARAMETER setting page, please set:
P+ (Potential Transformer ratio) = Ratio between Primary and secondary of the P/T. Set to: Vn/120.
If, for example Vn=3300V then set to: 3300/120=27.5.
C+ (C.Ts Primary) = 2.5 x Starter Rated Current.
Explanation of CT PRIMARY
: If The rated starter current is - for example - 1000A, its CTs (that are used
also for the MPS and DPM-10) are 1000 / 2A.
Please note that CTs secondary current is 2A, not 5A as of the DPM-10 and as of the MPS-3000 (See note 1
below).
When 1000A flows, the DPM-10 and MPS-3000 gets only 2A instead 5A and will calculate 2 / 5 x1000 = 400A.
Therefore we have to set the CT Primary to 1000x(5/2)=2500, which with 2A will read exactly 1000A as
required.
Notes:
1. In the MPS-3000 there is a second set of current transformers with a secondary of 1A. (Terminals 82,
85, 88 and 91).
In this case, when 1000A flows, the MPS-3000 gets 2A instead 1A and will calculate 2 / 1 x1000 = 2000A.
Therefore we have to set the CT Primary to 1000x(1/2)= 500, which with 2A will read exactly 1000A as
required.
2. In the MPS-3000 and DPM-10, each parameter has to be stored separately (while in the soft starter
you store all parameters of a page together).
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