What is Switchgear?
The combination of
- Electrical disconnect switches,
- Fuses
- Circuit breakers
that is used to regulate, protect, and isolate electrical equipment is referred to as switchgear.
What is Low-Voltage Switchgear?
Low-voltage switchgear is a 3-phase power distribution equipment designed to provide electric power safely, effectively, and reliably at voltages up to 1,000 volts and currents up to 6,000 amps. Typical ANSI/NEMA switchgear is rated for a maximum of 635 volts with a continuous current main bus rating of a maximum of 10,000 amps (for providing power from parallel sources).
Low-voltage switchgear is frequently found on a power distribution transformer’s secondary (low-voltage) side.
A substation is a transformer and switchgear combination. Low-voltage switchgear is commonly used to power
- Low-voltage motor control centers (LV-MCC),
- Switchboards, and
- Various branch and feeder circuits.
It is used to provide energy for critical power and critical process applications found in manufacturing, heavy industry, mining & metals, petrochemical, pulp and paper, utilities, water treatment, datacenters, and healthcare.
Overall Information
General
This standard describes low voltage switchgear assemblies.
To achieve system requirements, circuit breakers must have interrupting ratings & resist capabilities. Circuit breakers will be provided in frame sizes of 800, 1200, 1600, 2000, 2500, 3200, 4000, and 5000 A.
Constant Damp Heat
In this test, the effects of a constant, high humidity level (93 +/- 2%) and a constant temperature (40 2%) over a predetermined amount of time are examined.
Cyclic Damp Heat
The purpose of this test is to determine if electrical items are suitable for usage and storage in environments with high relative humidity levels and cyclical temperature fluctuations. A test cycle comprises of 12 hours at 40 2 °C and 93 3 % relative humidity and 12 hours at 25 3 °C and at least 95% relative humidity.
Ambient Temperature
The term “ambient temperature” refers to the temperature of the space (such as a manufacturing bay or switchgear room) in which an open or enclosed device is located, provided that the heat losses through the device have minimal or no effect on this temperature.
Terminology
This list provides brief definitions for some of the terminology used in this datasheet. However, it should not be viewed as a replacement for the real terminology of the standard, particularly when it comes to the new words used in IEC 947.
Rated Conditional Short-Circuit Current
The anticipated current that a switching device, such as a circuit breaker, can carry while being protected by a short-circuit protection device, such as a motor-protective circuit-breaker.
Minimum Command Time
Minimum time required for a trip-initiating factor (for example, a short circuit) to cause the associated reaction, such as the short-circuit duration required to commence tripping.
Rated Breaking Capacity
The R.M.S. value of current that a switching device has the capability of breaking based on its use category. The rated breaking capacity is expressed in terms of the rated operational voltage & current. The device must be equipped with breaking any current value up to and including its specified rated breaking capability.
Rated Actuating Voltage
In a control circuit, the voltage delivered to the actuating establish contact. This voltage can differ from the specified control supply voltage due to the inclusion of transformers (or) resistors in the control circuit.
Rated Service Short-Circuit Breaking Capacity
The anticipated short-circuit current that a circuit-breaker is designed for breaking repeatedly dependent on the rated operational voltage. After blocking this current flow, the circuit-breaker must be able to continue carrying and disconnecting the rated uninterrupted current even if its own heat level has increased.
Rated Power
According to the usage category, the rated operational power that an equipment has the capability of switching at the corresponding rated operational voltage.
Rated Operational Voltage
The voltage of which an equipment’s features are associated. In no situation may the rated operating current exceed the recommended insulation voltage.
Rated Operational Current
The current that an equipment can carry after accounting for the rated operating current, period of operation, usage category, and ambient temperature.
Technical Data Sheet for LV Switchgear
Instructions
- Kindly don’t change the formula-containing cells’ contents.
- To choose/go to the proper sheets, click the relevant TABS.
- Data is color-coded (yellow) in cells and columns and includes formulas and results. Data to be manually entered chosen from the drop down.
