
7–4
MM3 MOTOR MANAGER 3 – INSTRUCTION MANUAL
FUNCTIONAL TESTS
CHAPTER 7: TESTING
For average currents less than the motor full load:
,
with
(EQ 7.2)
where:
I
n
= RMS current in any phase with maximum deviation from the average current,
I
av
= average of the phase currents,
I
fl
= motor full load current,
I
a
= phase A current,
I
b
= phase B current, and
I
c
= phase C current.
7.2.2
Unbalance
Examples
EXAMPLE #1:
Find the percentage unbalance given the following information:
We have
I
av
given by:
(EQ 7.3)
Since
I
av
< I
fl
, the following formula is used:
(EQ 7.4)
Since the unbalance is greater than 15%, an unbalance alarm will occur if this condition
persists for longer than 5 seconds and auxiliary relay 1 will energize.
EXAMPLE #2:
Find the percentage of unbalance given the following information:
We have
I
av
given by:
(EQ 7.5)
Since
I
av
> I
fl
, the following formula is used:
(EQ 7.6)
Since unbalance is greater than 30%, a single phase trip will occur if this condition persists
for longer than 5 seconds and auxiliary relay 2 will energize.
I
n
I
av
–
I
fl
----------------
15% (alarm) 30% trip
>
I
av
I
a
I
b
I
c
+
+
3
------------------------
=
Value
Primary
Secondary (5 A)
Ia
73 A
3.65 A
Ib
100 A
5 A
Ic
100 A
5 A
Value
Primary
Secondary (5 A)
Ia
100 A
5 A
Ib
80 A
4 A
Ic
150 A
7.5 A
I
av
I
a
I
b
I
c
+
+
3
------------------------
73 100 100 A
+
+
3
-------------------------------------------
273
3
---------
A = 91 A
=
=
=
% unbalance
I
n
I
av
–
I
fl
-------------------
100
×
73 91
–
100
---------------------
100
×
18%
=
=
=
I
av
I
a
I
b
I
c
+
+
3
------------------------
100 80 150 A
+
+
3
-------------------------------------------
330
3
---------
A = 110 A
=
=
=
% unbalance
I
n
I
av
–
I
av
-------------------
100
×
150 110
–
110
----------------------------
100
×
36.4 %
=
=
=
Содержание MM3
Страница 8: ...vi MM3 MOTOR MANAGER 3 INSTRUCTION MANUAL TABLE OF CONTENTS ...
Страница 11: ...CHAPTER 1 INTRODUCTION OVERVIEW MM3 MOTOR MANAGER 3 INSTRUCTION MANUAL 1 3 Figure 1 1 Functional block diagram ...
Страница 18: ...1 10 MM3 MOTOR MANAGER 3 INSTRUCTION MANUAL TECHNICAL SPECIFICATIONS CHAPTER 1 INTRODUCTION ...
Страница 80: ...4 18 MM3 MOTOR MANAGER 3 INSTRUCTION MANUAL CHASSIS MOUNT UNITS CHAPTER 4 SOFTWARE ...
Страница 124: ...5 44 MM3 MOTOR MANAGER 3 INSTRUCTION MANUAL S7 TESTING CHAPTER 5 SETPOINTS ...
Страница 198: ...8 54 MM3 MOTOR MANAGER 3 INSTRUCTION MANUAL MODBUS MEMORY MAP CHAPTER 8 COMMUNICATIONS ...
Страница 220: ...10 14 MM3 MOTOR MANAGER 3 INSTRUCTION MANUAL GE MULTILIN WARRANTY CHAPTER 10 MISCELLANEOUS ...