Toshiba GR-200 Series Instruction Manual page 338

Motor current / Motor rated current
2.28.1
Motor current is used for the calculation of all motor protections and the motor rated current
is needed in the motor status judgement.
Motor current
(i)
There are two techniques, (i)-1 and (i)-2, to find the motor current; either is selectable by the
setting. The user has to determine which technique is to be used.
Use of Max. phase of I
The first technique is to use the largest phase-current among IL1, IL2, and IL3 as the
motor current, and it is expressed in Equation (2.28-1):
It is the same technique used in common thermal protection. It will be applicable when
Max is set for setting [Mot-Itype].
Use of positive and negative-phase sequence currents (I1 and I2)
The second technique is to use positive-phase sequence (I1) and negative-phase
sequence (I2) currents in the manner described in IEC 60255-149. It is expressed in
Equation (2.28-2):
where,
- ��
- ��
- q: Unbalance factor and selectable by the setting [Mot-Itype-q].
It will be applicable when Equivalent is set for setting [Mot-Itype].
Motor rated current
(ii)
The user has to defined a motor rated current with setting [Mot-Ir]. Equation (2.28-3) shows
the motor rated current (A) will be set in the MOT function.
Setting items
Mot-Ir
Mot-Itype
Mot-Itype-q
, I
L1 L2
Motor⁡current=Max⁡(I L1 , I L2 , I L3 )
Motor⁡current = ⁡ √ ��
1
＝
(�� + �� × �� + ��
1 ��1 ��2
3
1
＝ 2
(�� + �� × �� + �� × ��
2 ��1 ��2
3
Motor⁡rated⁡current⁡=⁡Setting[Mot-Ir]
Table 2.28-2 MOT current settings
Uni
Range
t
0.20 - 10.00 A Motor rated current
Max phase /
-
Selection of current for motor protection judgment
Equivalent
-
0 – 10 Factor q value given by setting [Mot-Itype]=Equivalent
- 319 -
or I
L3
⁡2 ⁡2
+ �� × ��
1 2
2
× �� )
��3
)
��3
Contents
6F2T0200 (0.15)
(2.28-1)
(2.28-2)
(2.28-3)
Default
1.00
Equivalent
0
GRE200 (1,2)