delta wiring

Voltage measurement

With existing Neutral

You can use the neutral as common reference for voltage measurement.

No Neutral

You can create a Neutral for voltage measurement with resistor or transformer network.

Or you can measure Line-Line. (Line 1 = common reference)

ATTENTION:

With Line-Line wiring, the whole PCB carries Line voltage. Use industry-standard precautions while operating.

Dump load wiring

This applies only to the variable dump load set. For the static dump loads, the order of the phases is not relevant.

the triac/SSR which is labeled "Line 1", connects the load from Line 1 to Line 2.

Triac/SSR Line 2: switches from L2 to L3

Triac/SSR Line 3: switches from L3 to L1

One important thing to keep in mind is that the optocoupler needs to be connected to MT2 of the triac. If MT2 is connected directly to a line, then the optocoupler can also be connected directly to this line.

If you mix up the sequence of the Lines, the trigger pulses will come in the wrong timing.

Test setup

Connect 2 light bulbs in series, parallel to each of the 3 variable dump loads. All 6 light bulbs should have the same brightness.

SSR wiring

Works only with random switching SSRs. Zero Crossing SSRs will not work with phase angle switching,

Use the first three SSR outputs, and configure these outputs in the menu settings / outputs / SSRs to function 9 - 10 (phase angle outputs).

Alternative: In the menu settings / outputs / variable dumpload, set to "zero crossing". Then zero crossing SSRs will work.

Triac wiring

If you want to use the triac drivers on the PCB, instead of random switching SSRs, you need to do modifications on the PCB.

PCB V1.2 and 1.3: the gate resistors have the wrong voltage rating, and need to be removed.

Cut tracks on PCB

The view is from the top. Both layers are visible. The top tracks are red. The bottom tracks are green. In the above screenshot, only the common neutral track is visible. It starts from pin 6 of the optocouplers, and goes to the bottom layer through the vias (white dots).

You need to cut the green track at the red/light blue marks, so pin 6 of the 3 MOC3052 optocouplers (ICs U29, U30 and U31) are not connected to anything and not to each other anymore.

Solder a wire to pin 6 of all 3 optocouplers.

Then connect this pin to MT2 of the correct triac, and the "other" line of your dump load.

The below screenshot illustrates the circuit

Line1 - load - MCB - inductivity - triac - Line 2

The order of the parts in this ciruit does not really matter.

Schematic for Line 1

The triac connects the load to Line 2.

The additional gate resistor is not shown.

2. Gate resistor

Add a series resistor of 330 Ohm between gate of the triac and the flat ribbon cable from the PCB connector "Triacs". This is to increase the peak voltage rating of the triac driver from 360V peak (250VAC) to 690V peak (480V AC)

To do: the gate resistors on the PCB V1.3 are only rated 200V DC. This is too low. Replace with 2 resistors in series

3. Snubber circuit

The phase angle triacs disturb each other in Line-Line configuration.

During the switching point of one triac on one phase, the voltage changes so much on this phase, that it triggers the other triacs at certain angles.

-> Add 100nF high voltage and 100 Ohm in series from MT1 to MT2.

Other suppression methods which DID NOT work:

- add a capacitor 10nf - 220nf from Gate to MT1, in order to reduce spikes on the gate. This helped, but not enough. And it increases the peak current through the optocoupler, and reduces switching speed.

- shield cables to gate.

Did not help at all, Since the disturbance is not on the gate wire, but on the phase wire.

- connect optcouplers directly to the triac, rather than to a common point on the PCB

Did not help. The gate wire is not the problem.

- add capacitors on the optocouplers.

Did not help. The optocoupler signal is clean.

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