SDV-DM7 AC200/220 Omron, SDV-DM7 AC200/220 Datasheet - Page 37

• Manufacturer Part Number: SDV-DM7 AC200/220
• Description: Sensor Hardware & Accessories VOLTAGE SENSOR
• Manufacturer: Omron

Specifications of SDV-DM7 AC200/220

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

If the motor is run by thyristor phase control, the motor current wave-
form will be changed by the control angle, and even a small leading
angle can cause malfunctions in the SE relay.
The example on the following page shows the primary current and
the output waveform of the SET-3@. When the AC component of the
output is large, an SE-series relay misjudges it as open phase.
The unbalanced factor can be obtained easily from the following
graph. In the graph, the horizontal axis indicates the phase of the
maximum current, whereas the two vertical axes indicate the remain-
ing two phases. Taking the phase of the maximum current with a ref-
erence value of 1.0, the unbalanced factor is obtained in percentage
from the curves centered in the graph.
Load current: 2.50 A
SET-3A output voltage: 21.00 VDC
Phase control angle: 76
Normal Three-phase Output
Output with an Unbalance
Load current: 2.50 A
SET-3A output voltage: 21.77 VDC
Phase control angle: 11
3.54 A
Calculating the Unbalanced
Factor
0
0
3.54 A
76
5 V
11
5 V
10 ms
10 ms
Output voltage
Output voltage
Current
Current
rms
rms
Output with a Open-phase
Average
DC Value
When the motor current I
the ratios of the currents, setting the value of the maximum current to
1. In this case the ratios are 1 : 0.6 : 0.7 (I
To find the unbalanced factor, follow the arcs from the ratio values on
the vertical axes, in this case 0.6 and 0.7, to their intersection point.
The unbalanced factor can be estimated from the values on the
graph. Here the unbalanced factor is approx. 36%.
Motor Protective Relay
R
= 100 A, I
s
= 60 A, and I
R
: I
S
: I
T
SE
).
T
= 70 A, calculate
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