|
APPLICATION NOTE - 1003
Selecting
an SCR Power Control or Transformer Coupled RF Induction Loads
Author - George A. Sites, Director of Engineering AMETEK HDR Power Systems
INTRODUCTION
In almost all RF Induction heating applications, it seems that arcing
or shorting on the secondary is common. This is not a major problem using
an SCR Power Control that is fused and equipped with an Overcurrent Trip
circuit. However, in many of these applications the engineer designing
the equipment uses power controllers without line fuses to help prevent
nuisance fuse blowing. There is one disadvantage with this practice,
the SCR Power Control must be oversized to handle the surge currents
resulting from the short circuits. The intent of this Application Note
is to provide help in selecting an HDR power control without fuses based
on line voltage, transformer impedance and load kilowatts.
CAUTION
AMETEK HDR Power Systems recommends the use of line fuses on all
SCR Power Controls. However, use this information to help prevent damaging
the SCR if operating without fuses. The user must provide adequate
overcurrent protection.
SELECTION CRITERIA To properly select the correctly sized non-fused SCR Power Control you
must have the following information: the AC input voltage; the transformer
impedance and the required load kilowatts.
Refer to the table on page 2 for 1-phase systems and page 3 for 3-phase
systems. The information is grouped according to the standard current
ratings of AMETEK HDR Power Controls. Locate the current rating column
and then find the current rating of the SCR Power Control you intend
on using. Next go to the right on the same line as the voltage rating
and find the column with the transformer impedance. Listed is the load
kilowatt rating for that particular sized unit. Also included for your
reference is the normal kilowatt rating of the power control if fused.
NOTE:
This Application Note is intended for informational and illustration purposes
only. Actual applications may differ. Contact the HDR factory for information
on your exact requirements.
© 2005
|
SINGLE-PHASE
LOAD KILOWATT RATINGS
|
|
|
|
NON
- FUSED KILOWATTW RATINGS
TRANSFORMER
IMPEDANCE
|
|
|
1PH
VOLTAGE
|
CURRENT
RATING
|
4%
|
5%
|
6%
|
7%
|
FUSED
|
|
600
480
400
240
120
|
60
60
60
60
60
|
33
26
22
13
6
|
35
28
24
14
8
|
35
28
24
14
8
|
35
28
24
14
8
|
35
28
24
14
8
|
|
600
480
400
240
120
|
90
90
90
90
90
|
49
39
32
20
9
|
54
43
35
21
10
|
54
43
35
21
10
|
54
43
35
21
10
|
54
43
35
21
10
|
|
600
480
400
240
120
|
120
120
120
120
120
|
49
39
32
20
9
|
61
49
40
24
12
|
72
57
47
28
14
|
72
57
47
28
14
|
72
57
47
28
14
|
|
600
480
400
240
120
|
180
180
180
180
180
|
98
78
65
39
19
|
107
86
72
43
21
|
107
86
72
43
21
|
107
86
72
43
21
|
107
86
72
43
21
|
|
600
480
400
240
120
|
225
225
225
225
225
|
105
84
69
42
21
|
131
105
87
52
26
|
135
107
90
54
27
|
135
107
90
54
27
|
135
107
90
54
27
|
|
600
480
400
240
120
|
350
350
350
350
350
|
117
93
77
46
23
|
146
117
97
58
29
|
172
137
114
68
34
|
210
168
139
83
42
|
210
168
139
83
42
|
|
600
480
400
240
120
|
500
500
500
500
500
|
165
132
110
65
33
|
206
165
137
82
41
|
243
194
162
96
48
|
295
236
196
117
59
|
300
240
200
120
60
|
|
600
480
400
240
120
|
650
650
650
650
650
|
299
239
199
119
60
|
374
299
250
149
75
|
389
311
259
155
78
|
389
311
259
155
78
|
389
311
259
155
78
|
|
600
480
400
240
120
|
800
800
800
800
800
|
299
239
199
119
60
|
374
299
250
149
75
|
441
352
293
176
78
|
479
383
319
192
96
|
479
383
319
192
96
|
|
600
480
400
240
120
|
1000
1000
1000
1000
1000
|
575
460
383
230
115
|
599
479
400
240
120
|
599
479
400
240
120
|
599
479
400
240
120
|
599
479
400
240
120
|
|
600
480
400
240
120
|
1200
1200
1200
1200
1200
|
575
460
383
230
115
|
719
576
479
288
144
|
719
576
479
288
144
|
719
576
479
288
144
|
719
576
479
288
144
|
|
THREE-PHASE
LOAD KILOWATT RATINGS
|
|
|
|
NON
- FUSED KILOWATT RATINGS
TRANSFORMER
IMPEDANCE
|
|
|
3PH
VOLTAGE
|
CURRENT
RATING
|
4%
|
5%
|
6%
|
7%
|
FUSED
|
|
600
480
400
240
208
|
60
60
60
60
60
|
58
46
38
23
20
|
62
50
42
25
22
|
62
50
42
25
22
|
62
50
42
25
22
|
62
50
42
25
22
|
|
600
480
400
240
208
|
90
90
90
90
90
|
85
68
57
35
30
|
94
75
62
37
32
|
94
75
62
37
32
|
94
75
62
37
32
|
94
75
62
37
32
|
|
600
480
400
240
208
|
120
120
120
120
120
|
85
68
57
35
30
|
106
85
71
42
37
|
125
100
83
50
43
|
125
100
83
50
43
|
125
100
83
50
43
|
|
600
480
400
240
208
|
180
180
180
180
180
|
170
136
113
68
59
|
187
150
125
75
65
|
187
150
125
75
65
|
187
150
125
75
65
|
187
150
125
75
65
|
|
600
480
400
240
208
|
225
225
225
225
225
|
182
146
121
73
63
|
228
182
152
91
79
|
234
187
156
94
81
|
234
187
156
94
81
|
234
187
156
94
81
|
|
600
480
400
240
208
|
350
350
350
350
350
|
203
162
135
81
70
|
254
203
169
101
88
|
299
239
199
119
103
|
364
291
242
145
126
|
364
291
242
145
126
|
|
600
480
400
240
208
|
500
500
500
500
500
|
286
229
191
114
99
|
358
286
239
143
124
|
421
337
281
168
146
|
512
409
341
204
177
|
520
416
346
208
180
|
|
600
480
400
240
208
|
650
650
650
650
650
|
519
415
346
207
180
|
649
519
433
259
225
|
675
540
450
270
234
|
675
540
450
270
234
|
675
540
450
270
234
|
|
600
480
400
240
208
|
800
800
800
800
800
|
519
415
346
207
180
|
649
519
433
259
225
|
764
611
509
305
264
|
831
665
554
333
288
|
831
665
554
333
288
|
|
600
480
400
240
208
|
1000
1000
1000
1000
1000
|
997
798
665
399
345
|
1039
831
693
416
360
|
1039
831
693
416
360
|
1039
831
693
416
360
|
1039
831
693
416
360
|
|
600
480
400
240
208
|
1200
1200
1200
1200
1200
|
997
798
665
399
345
|
1247
998
831
499
432
|
1247
998
831
499
432
|
1247
998
831
499
432
|
1247
998
831
499
432
|
|
