Nederman VAC 12/20 Manual De Instrucciones página 27

8.2.4 Adjusting the Anti surge control
Note that the I -dial (the upper dial) is graduated 10-100%. The current
e
transformer characteristics and the wiring of the transformer to the current
sensing relays, make the graduation of the scale equal to 10–100 A.
Stop the vacuum unit. The ducting is to be completely sealed off with all
outlets closed. Close the dust collector inlet with a hard board if there is no
guarantee that the ducting will be closed.
Check the settings of the current sensing relays according to Figure 21. Make
sure the slide switches on the underside of the relays are set according to the
figure. Figure 19 shows loosening of the relays from the DIN rail using a screw
driver. All relay settings except for I
possible and I
e max
Switch on the start and control unit main switch but do not start the vacuum
unit. The green LEDs marked U
LED (Light Emitting Diode) marked R on MIN.
Start the vacuum unit. The characteristic pumping sound is to be heard. No
yellow LED is to light up. Slowly increase I
The valve inside the vacuum unit opens a little and the yellow LED goes out
again. Repeat until the vacuum unit runs smoothly without pumping. For large
units (30 kW or more) this occurs close to the point where the valve is fully
open and the yellow LED will not go out as I
point. For such a unit, set I
The figures in 'Table 8-1: Guidelines for Ie min for 3×400 V' can be used as a
guideline for 3×400 V.
Table 8-1: Guidelines for I
Motor, kW
22
30
37
45
For other supply voltages, calculate a rough I
• 400/actual voltage × (I
Example for 460 V, 40 hp:
• I =400/460x32≈28 A.
e min
Then set I to a value about 5 units higher than I
e max
occurs, resulting in repeated opening and closing of the valve, increase the
dead band by setting I
Testing the Anti surge control settings
Slowly increase the flow through the fan by opening a valve (or sliding aside
the board blocking the collector inlet). The yellow MIN LED should go out
(if it has been lit) and the MAX LED should light up if the flow is further
increased. As the flow is gradually increased, the valve closes more and
more until it is fully closed and I
installation in full use this is a normal situation.
Block the flow rapidly and check that the valve finds a balancing point within a
few seconds without self-oscillating. This terminates the test.
% are to be set to zero. Set I
e
as high as possible.
on both relays light up as well as the yellow
N
so that the LED is lit continuously, no higher.
e min
for 3×400 V
e min
hp
30
40
50
60
for 400 V).
e min
slightly higher.
e max
lights up yellow continuously. For an
e max
VAC 12/20
e min
until the yellow LED lights up.
e min
is increased beyond a certain
e min
I , A
e min.
25
32
33
33
setting as follows:
e min
. If self-oscillating
e min
EN
as low as
27