PTE-50-CET
Sheet 24
e) Phase selection displays
The display is made up of 4 digits of 7 segments, red in
color and 0.3 inches in height, which shows the selected
values.
3.4.
CHANNELS IN PARALLEL
3.4.1. USE
When the channels are connected in parallel, we are actually looking for
more power
than only one
channel can give, not always for higher current.
We must realize that one output channel, of PTE-50-CET, can supply 100 VA as maximum. This
means that for each output tap we have a voltage value that cannot be exceeded:
Tap
Maximum
voltage
0.33 A
150 V
8 A
Booster OFF
6.25 V
Booster ON
12.5 V
25 A
Booster OFF
2 V
Booster ON
4 V
50 A
Booster OFF
1 V
Booster ON
2 V
In fact, the only electrical parameter with a real physical sense, by itself, is voltage. We cannot define
a current supply in terms of current capacity only, but we need to define the maximum load that can
be connected to the taps, to reach the current limit.
Suppose we have the burden of a relay (15 VA) at the nominal current (5 A). We can calculate its
internal impedance using the
Ohm’s Law
:
VA
LOAD
= I
LOAD
×
V
LOAD
⇒
V
LOAD
= VA
LOAD
/ I
LOAD
= 15/5 = 3 V
Z
LOAD
= V
LOAD
/ I
LOAD
= 3/5 = 0.6 A
This means that if you want to inject 5 A in this relay a 3 V voltage is needed, so a 15 VA power from
the injection equipment.
If you select the 25 A tap (Booster ON), on PTE-50-CET, you can inject this current to the relay,
because 3V
<
4V (maximum voltage drop). Instead, if we select the 50 A tap, you can’t get sufficient
voltage (3V
>
2V), so the test can’t be performed.
3.4.2. CONNECTION
If we want the channels of PTE-50-CET, to work in parallel, it is necessary that the outputs are
connected in the way shown below: