Fuses, Evaluating motorguard performance, Typical vfd waveforms without filtering – TCI KMG User Manual
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Fuses
Table 12 lists the specifications for the RC power circuit fuses in the MotorGuard.
Table 12 – RC Power Circuit Fuses for Industrial Model
480 V Models
600 V Models
MotorGuard
Rating
(Amps)
Power Circuit
Fuse Rating
MotorGuard
Rating
(Amps)
Power Circuit
Fuse Rating
Amps
Type
Amps
Type
8
2
Class CC
Bussmann
type KLD-R
or equivalent
8
2
Class CC
Bussmann
type KLD-R
or equivalent
12
2.5
10
2
16
4
12
2.5
23
6
20
5
30
8
25
6
35
9
28
7
45
12
35
9
55
15
45
12
65
20
55
15
80
20
65
20
110
30
Class T
Bussmann
type JJS
or equivalent
80
25
130
35
110
30
Class T
Bussmann
type JJS
or equivalent
160
40
130
35
200
50
160
40
250
70
200
50
305
80
250
70
362
90
305
80
420
110
362
90
480
125
420
110
600
150
500
125
750
200
600
150
Control Circuit Fuses
Refer to the drawings furnished with your MotorGuard for control circuit fuse specifications.
Evaluating MotorGuard Performance
The MotorGuard performance can be evaluated by checking the output voltage waveform with an
oscilloscope.
Warning
Only qualified electricians should carry out all electrical installation and maintenance work on
the MotorGuard.
Exercise caution when checking waveforms with an oscilloscope.
Use a dual probe, differential input set-up, or other means of isolating the scope chassis from
the motor voltage.
Disconnect power when attaching and removing the probes.
Typical VFD Waveforms without Filtering
Figure 6 shows two examples of output voltage waveforms for a typical PWM variable frequency
drive. The example labeled "VFD Output Voltage Waveform" is a "clean" waveform as it would
appear with nothing connected to the VFD output terminals. The voltage peaks of this waveform are
about 650 volts for a 480 volt drive. The example labeled "Motor Voltage Waveform" shows the