MPA3 V6.3 MOTOR PROTECTION RELAY MANUAL
Issue: R0, Date: 11/2010, CRN: 8168
MPAB010 Rev0
MPA3 V6.2 Motor Protection Relay Manual
Page 11
5
Current Related Functions
5.1
Overload Protection
The motor overload function is based on a thermal model of the motor. The three phase currents are squared to
provide the
I
2
R
heating input to the motor model. The selected ‘Stopped Cooling Ratio’ determines the cooling
output for the model.
The state of the thermal model is shown by the ‘Thermal Accumulator’, which can be viewed on the 'Current/Volts
Information' level on the display. The thermal accumulator represents the motor temperature. When it reaches 100%
a “Motor Overload” trip occurs.
The full load current is selected via the ‘
I (100%)
’ setting (Level 7, Position 1) and can be set between 5.125 A and
640 A in 224 increments as shown in Table 5.1, ‘Current Settings’.
MPA Full Load Current Selection Table - Amps
5.125 7.000 10.000 14.00 20.00 28.0 40.0
56
80
110
160
220
320 440
5.250 7.125 10.25 14.25 20.5 28.5
41
57
82
112
164
224
328 448
5.375 7.250 10.50 14.50 21.0 29.0
42
58
84
114
168
228
336 456
5.500 7.375 10.75 14.75 21.5 29.5
43
59
86
116
172
232
344 464
5.625 7.500 11.00 15.00 22.0 30.0
44
60
88
118
176
236
352 472
5.750 7.625 11.25 15.25 22.5 30.5
45
61
90
120
180
240
360 480
5.875 7.750 11.50 15.50 23.0 31.0
46
62
92
122
184
244
368 488
6.000 7.875 11.75 15.75 23.5 31.5
47
63
94
124
188
248
376 496
6.125 8.000 12.00 16.00 24.0 32.0
48
64
96
126
192
252
384 504
6.250 8.500 12.25 17.00 24.5 34.0
49
68
98
128
196
256
392 512
6.375 8.750 12.50 17.50 25.0 35.0
50
70
100
136
200
272
400 544
6.500 9.000 12.75 18.00 25.5 36.0
51
72
102
140
204
280
408 560
6.625 9.250 13.00 18.50 26.0 37.0
52
74
104
144
208
288
416 576
6.750 9.500 13.25 19.00 26.5 38.0
53
76
106
148
212
296
424 592
6.875 9.750 13.50 19.50 27.0 39.0
54
78
108
152
216
304
432 608
13.75
27.5
55
156
312
624
640
Table 5.1 Current Settings
