LSIG protection means Long-time, Short-time, Instantaneous and Ground-fault protection. These functions describe how a compatible electronic trip unit responds to overload and fault conditions. Availability depends on the installed trip unit, so an MCCB’s current rating or LCD display alone does not confirm full LSIG protection.
For panel builders, distributors and project buyers, the purchasing question is whether the quoted breaker provides the required functions and documented settings. Send NUOMAK your MCCB specification to discuss available sourcing options.
LSIG-bescherming in MCCB begrijpen
| Functie | Doel | Common parameters |
|---|---|---|
| L — Long-time | Bescherming tegen overbelasting | Ir pickup; tr delay where provided |
| S — Short-time | Short-circuit protection with a delay characteristic | Isd pickup; tsd delay where provided |
| I — Instantaneous | Short-circuit protection without an intentional delay | Ii pickup |
| G — Ground-fault | Earth-fault protection using the supported detection method | Ig pickup; tg delay where provided |
The table describes common electronic trip unit terminology. It is not a feature list for every MCCB or a set of recommended operating settings.
Understanding the Four LSIG Protection Functions
L — Long-Time Overload Protection
Long-time protection responds to sustained overload according to the trip unit’s time-current characteristic. Its pickup is commonly marked Ir. A delay control may also be available. Check the documented range and characteristic for the quoted configuration.
S — Short-Time Short-Circuit Protection
Short-time protection uses a pickup and delay characteristic to respond to short-circuit current. Isd commonly identifies the pickup, while tsd identifies the delay. The delay can support coordination with downstream protection; it does not mean the function only detects faults that last briefly. Some models have a fixed delay.
I — Instantaneous Short-Circuit Protection
Instantaneous protection responds without an intentional delay when its operating conditions are met. Ii commonly identifies its pickup. It is separate from Isd, and the breaker still takes finite time to open and clear the fault. The pickup may be fixed or adjustable.
G — Ground-Fault Protection
Ground-fault protection responds to earth-fault current using the detection method supported by the device. Pickup and delay settings depend on the configuration. Do not assume this function replaces residual current protection intended for personnel protection; verify the protection type and sensitivity required for the installation.
Why LSIG Matters When Comparing MCCBs
Two breakers with the same current rating may offer different protection functions. A buyer comparing an existing breaker with a proposed replacement should request the trip unit designation and supported functions, rather than relying on the frame size or screen appearance.
LSIG functionality also does not establish a product’s certification or breaking capacity. Check the relevant reports, applicable standards and Icu/Ics ratings separately. For the relationship between overload and short-time markings, see Io, Ir and Isd in MCCB trip settings.
How Should LSIG Settings Be Selected?
There is no universal LSIG multiplier suitable for every installation. The documented ranges, current references and time-current curves must be interpreted for the exact device. Application settings should be determined through the installation’s electrical protection assessment.
For purchasing, collect the required functions and manufacturer documentation. For commissioning, the electrical designer or protection specialist must assess the installation and coordination requirements. A general article cannot substitute for that assessment.
What to Include in an LSIG MCCB Inquiry
| Information | What to send |
|---|---|
| Existing equipment | Breaker and trip unit model, or clear nameplate and front-panel photos. |
| Electrical requirements | Required current, voltage, frequency, poles and specified breaking capacity. |
| Protection requirements | Required L/S/I/G functions and any settings specified by the project designer. |
| Installation details | Dimensions, mounting, terminals and accessories where specified. |
| Order requirements | Quantity, destination market, delivery needs and any branding request. |
If some details are unknown, send the information you have and identify what needs clarification. Photos help identify the device, but they do not establish full replacement suitability.
Checking LSIG Options When Sourcing from NUOMAK
Review AC LCD adjustable current MCCB options as a starting point for display-equipped products, or browse AC adjustable current MCCBs for other adjustable configurations. The supplying manufacturer’s documentation must confirm the functions of the proposed model before it is specified as LSIG.
Request a Model-Specific MCCB Quotation
Send your required functions, electrical ratings and quantity. NUOMAK can coordinate with the supplying manufacturer to check available configurations and supporting documentation. Include an existing model or project specification if you have one.
Request MCCB Options and a Quote
Veelgestelde vragen
Is LSIG available on every MCCB?
No. The installed trip unit determines the available functions. Fixed thermal-magnetic or other electronic configurations may not provide all four functions.
Does an LCD screen mean the breaker has LSIG?
No. A display is not evidence of full LSIG protection. Request the model’s supported-function list and manual.
What is the difference between Isd and Ii?
Isd is associated with short-time protection in the electronic configurations discussed here. Ii is associated with instantaneous protection. They must not be treated as the same setting.
Does ground-fault protection replace a personnel-protection residual current device?
Do not assume it does. Detection method, sensitivity and installation requirements must be checked for the proposed device.
How can I check an MCCB option before placing an order?
Provide the breaker and trip unit model or your purchase specification. Ask for confirmation of supported functions, adjustment ranges, breaking capacity at the required voltage, dimensions and available documentation.
Discuss Your Project or Wholesale Order
Contact NUOMAK with your current rating, voltage, required protection functions and quantity. If you are comparing a replacement, add the existing model and any available photos. You can send photos through WhatsAppen to begin the sourcing discussion.
Send Your MCCB Purchase Requirements
-
Reference: Schneider Electric MicroLogic technical documentation. These explanations describe common terminology; functions and settings must be verified for the exact model being supplied.
