Technical Articles
Dual Protection Set Group is a feature in Protective Devices wherein two sets of protection settings can be saved in its permanent memory and we can switch between the two as per the requirement. The two set groups are referred to as Active Set Group and Dormant Set group.
These parameters may include complete set of protection settings like delay settings, pickup current, cold pickup parameters, directional settings, etc. It is primarily useful where different setting of Air Circuit Breaker is required at different times of the day due to pattern of the load changing with time.
As an illustrative case, consider the case of a commercial mall. The mall opens at 10AM in the morning and closes at 11PM in the night. During this time, the mall has several appliances, lighting loads, HVACs Loads, and other Motor loads (for escalators and lifts). During night-time (no load hours), all these loads will be shut down, except for a few lights. So, the protection settings of the circuit breaker required at both these times are naturally going to be different.
With Dual Protection Set Group, The different protection settings can be saved under two different “Set Groups” in the Release settings and each Set Group can be enabled after a predefined set time, or by a command. So, in the morning just before the mall opens, the Set Group 1 will be activated.
Consider a distribution system wherein the main supply is being distributed through ACB1 feeder and in the downstream load is being catered through various MCCB feeders. In our illustrative case, MCCB 1, 2 and 3 would be supplying loads such as HVAC and Motor Loads, while MCCB 4 will be supplying common lighting loads. Here ACB acts as a backup protection device for MCCB feeders.
as shown in the figure below. ACB1 is the upstream ACB and downstream connected are MCCBs 1, 2, 3 and 4, each connected to their respective loads. Out of these MCCB4 has lighting loads connected. Here the ACB as well as the MCCBs have their own protection settings.
Say the system is on low load condition (during night/maintenance) and a fault happens to occur in the zone of MCCB-4.
If MCCB-4 fails to operate, then the upstream ACB must trip to clear the fault. But since the ACB protection settings are set according to loaded conditions, whereas the system is in fact operating at low load condition, the upstream ACB may fail to clear the low magnitude fault. This can cause hazardous conditions like fire.
If MCCB-4 fails to operate, then the upstream ACB, in this case, owing to its lower protection thresholds will clear the fault. This will ensure complete safety of the system in load as well as no load hours.
During normal conditions, Set Group 1 with Nominal Protection thresholds can be enabled. During low load conditions like during night/maintenance, Set Group 2 with Lower Protection thresholds (according to non-peak hour requirements) can be enabled.
Dual Protection Set Group feature is essential in cases where load is pattern is changing with respect to time in a day. Suitable for commercial, residential, and industrial applications. Typical applications include factories, offices, malls, etc. This feature is also immensely useful during maintenance activities.
Starting from MTX3.5, all releases come with built in feature of Dual Protection Set Groups. These can be set according to Real Time Clock or set to activate after a pre-defined time. This enables an automated protection, thus ensuring real time safety.
| Features | MTX3.5 | MTX3.5EC | MTX3.5H | MTX4.5 |
|---|---|---|---|---|
| Storable Settings (2 Sets) | ✔ | ✔ | ✔ | ✔ |
L&T E&A’s Omega range of ACB are equipped with three modes for switching between Active/Dormant Set Groups:
In Auto Set Group Mode, if we set the time for SG1 as 06 hrs and 20 mins, and the time for SG2 as 14hrs and 40mins, then every day at 06:20 AM in the morning the SG1 will get activated while SG2 will remain dormant. Likewise at 02:40PM in the afternoon, SG2 will get activated and SG1 will become dormant. This pattern shall run continuously every day.
“The protection releases shall offer Dual time-based protection set groups working on Real-Time Clock basis for ensuring full protection of system during load and no-load hours.”
| Feature | OMEGA | MTZ | NW | MVS | Emax2 | Emax | Formula | 3WL | 3WT | DMX3 |
|---|---|---|---|---|---|---|---|---|---|---|
| Dual Set Group based on RTC | MTX3.5 onwards | Yes (Optional) | No | No | Ekip Hi-Touch | PR123 | No | ETU76B | No | No |
Rajesh R Shirodkar,
DGM-Corporate CommunicationRajesh Shirodkar is a seasoned marketing and business leader with over 20 years of experience in the automation and electrical industry, spanning marketing communications, sales, business development, and software solution selling. He has led successful brand transformation initiatives and high-impact marketing programs, including branding and account-based marketing campaigns, as well as industry events that drive visibility, engagement, and growth. With expertise in brand building, lead generation, solution selling, and sales enablement, Rajesh is known for translating technology and business offerings into compelling value propositions and delivering sustainable growth through strong stakeholder collaboration.
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