A single DTC1000V voltage output can control three three-phase SSR assemblies only when their combined control-input current does not exceed 40 mA. Base this decision on the SSR control-terminal current, not the heaters’ load current or phase arrangement.
Calculate the OUT1 Control Load
Read the maximum control-input current from each SSR specification and add the values. Parallel operation is supported by the available evidence only when the total remains within the DTC1000V’s stated 40 mA output limit.
If all three SSR inputs draw the same current, each may draw no more than 40 mA / 3 = 13.33 mA under this calculation. Do not use the SSR power-output current rating in place of its control-input current.
Select the Drive Architecture
| Method | When to use it | Evidence-based constraint |
|---|---|---|
| Three SSR inputs on OUT1 | The summed input current is within 40 mA | Calculate the total from the SSR control-terminal requirements |
| OUT2 relay with an external supply | OUT1 cannot supply every SSR input | The relay switches the external 12 V control circuit and physically opens and closes |
| Intermediate slim SSR | A mechanical relay is unsuitable for the required switching | A 3 A output was proposed, but verify the selected interface relay’s actual input and output ratings |
Configure and Wire the Supported Alternatives
- For direct parallel control, connect the SSR control inputs to OUT1 only after confirming that their summed input current is no greater than 40 mA.
- If the total exceeds 40 mA, configure both controller outputs for heating so they operate together. Use the OUT2 relay contact to switch an external 12 V supply to the additional SSR control input.
- If relay operation is too slow or otherwise unsuitable, drive an intermediate slim SSR from the DTC1000V voltage output, then use its output to control the heating SSR inputs. Verify compatibility and ratings before wiring.
OUT2 is a relay output, so it will open and close during control. Confirm that this behavior matches the required heating-control cycle before selecting it.
Keep One Temperature-Control Loop
Adding another DTC controller does not create a synchronized extension of the first controller; the evidence states that it operates independently. The evidence does not establish that branching one NiCr-Ni thermocouple directly into two controller inputs preserves measurement accuracy, so do not assume that arrangement is valid. Prefer one measurement and one controller driving properly sized interface hardware.
FAQ
Can one DTC1000V output drive three SSRs?
Yes, if the sum of all three SSR control-input currents is no greater than 40 mA. For three equal inputs, the calculated limit is 13.33 mA per SSR.
How do I control another SSR when DTC1000V OUT1 exceeds 40 mA?
Configure OUT2 for heating and use its relay contact to switch an external 12 V supply to the additional SSR control input. Account for the relay physically opening and closing.
Can two DTC controllers share one NiCr-Ni thermocouple?
The available evidence does not confirm that directly branching the thermocouple maintains measurement accuracy, and the two controllers would operate independently. Use one controller with a rated interface stage unless the controller and sensor documentation explicitly supports sharing.