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title: "Configuring Flow Rate-of-Change Constraints for a Regulator"
canonical: "https://docs.rubiconwater.com/space/PNC/2051899679/Configuring%20Flow%20Rate-of-Change%20Constraints%20for%20a%20Regulator"
format: markdown
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> Macro (toc)

> ℹ️ **Note**
> ℹ️ 
> ℹ️ This feature is disabled by default. Contact Rubicon Support if you want to use it.

# What is a rate of change constraint?

A rate of change constraint limits the *change* in flow rate that can be applied at a regulator as a result of changes in demand in the downstream channel. These checks are in addition to the maximum flow rate check that ensures that a regulator does not exceed its maximum flow rate.

> ℹ️ **Note**
> ℹ️ 
> ℹ️ This is different from flow rate-of-change constraints that can be set on *outlets* where TCC mode is Partial. See [https://rubiconwater.atlassian.net/wiki/spaces/PNC/pages/2051866912](https://rubiconwater.atlassian.net/wiki/spaces/PNC/pages/2051866912) for details.

# How are rate of change constraints configured for a regulator?

Rate of Change constraints are configured by setting the following attributes at the regulator.

| **Attribute** | **Description** |
| --- | --- |
| DMS ROC Enabled | Set to YES or NO to enable or disable rate of change checking at this regulator. The default is NO . |
| DMS ROC Max Flow Step | This specifies the maximum flow rate change than can be passed by the regulator. |
| DMS ROC Recovery Time | This specifies the minimum time gap between two maximum flow change steps. |

# Are checks applied for both increases and decreases in flow rate?

Yes, by default the system checks both increases and decreases in flow rate. However, it is possible to configure the feature to check only increases in flow rate. Contact Rubicon Support if you need to do this.

> ℹ️ **Note**
> ℹ️ 
> ℹ️ Limits on decreasing flow rate are NOT applied when an order is cancelled.

# How is this constraint applied?

The irrigator will be alerted if their order has violated any Rate of Change constraints that required their order to be rescheduled or rejected.

> ℹ️ **Note**
> ℹ️ 
> ℹ️ You should communicate to irrigators that rate-of-change constraints are being applied so that they understand that orders may be rejected even when there appears to be capacity in the network.
> ℹ️ 
> ℹ️ They should also be advised that rate-of-change restrictions will not prevent them from cancelling orders.

## If a Single Order Exceeds the Max Flow Step

If a single order exceeds the maximum flow step, the order may be:

- Rescheduled to fall between other orders so that the change in *overall* flow through the channel is less.
- Rejected, in which case the irrigator may need to split the order into a multi-flow order with staggered start and end times.

## If the Last of Several Orders Exceeds the Max Flow Step

If several orders have already been scheduled, and a further order pushes the upstream regulator past it's maximum flow step (at either the start or the end of the order), the last order placed will be rescheduled.

Note that when the maximum flow change is reached, there is a delay period - the DMS ROC Recovery Time - before another maximum flow change can be made. If the next flow change is smaller than the maximum, a recovery time will still apply but it will be reduced in proportion to the flow change.

> ℹ️ **Example**
> ℹ️ 
> ℹ️ - If a *Max Flow Step* has been reached at a regulator, and there is another order that requires another *Max Flow Step*, then the next order cannot start before the full *Recovery Time* has elapsed.
> ℹ️ - If a *Max Flow Step* has been reached at a regulator, and there is another order that requires half of the *Max Flow Step*, then the actual recovery time will be half of the full *Recovery Time*.

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