Industry — Oil & Gas
Switchgear and power distribution centers engineered for classified areas and remote sites
Oil and gas facilities put power equipment in hot, corrosive and often hazardous environments, far from spare parts and skilled labor. Apex engineers low- and medium-voltage switchgear, packages it into E-houses and power distribution centers, and integrates motor protection and remote monitoring so operators can see the electrical system from the control room.
Operating realities
What makes oil & gas distribution its own discipline
Equipment location in classified areas
Switchgear is not built for Class I, Division 2 or Zone 2 atmospheres, so the practical design question is where to put it. The usual answers are a pressurized or purged E-house, an unclassified area established by the area classification study, or a PDC sited at the edge of the process. Area classification, ventilation and gas detection are decided with the process and HSE teams, not by the switchgear supplier alone.
Large motor loads and their protection
Compressors, pumps and fans driven by medium-voltage motors dominate the load and the protection scheme. Motor protection relays with thermal (49), locked-rotor, negative-sequence (46) and differential (87) functions have to be coordinated with starting methods, drive front ends and upstream breakers. IEEE 841 and API-specified motors bring their own data that the relay settings must respect.
Packaging, transport and site conditions
An E-house or PDC has to arrive as a tested unit: switchgear, transformers, MCCs, HVAC, fire detection and cable management engineered on one skid or building. Transport dimensions, lifting points, seismic and wind loads and ambient temperature ratings are settled with the structural and mechanical disciplines early. Corrosion protection and HVAC redundancy matter as much as the electrical one-line in coastal and desert sites.
Weak utility supply and onsite generation
Many sites run on generators, or on a utility feed too weak to start the largest motor. Generator paralleling, load shedding and soft-start or drive-based starting have to be coordinated so a compressor start does not trip the plant. Islanded operation changes fault current levels, which changes relay settings and coordination.
How Apex fits
LV, MV, automation and monitoring for oil & gas
Low-voltage equipment
480 V switchgear and MCC coordination
Apex engineers UL 1558 low-voltage power switchgear and UL 891 switchboards for E-house and PDC distribution, coordinated with the MCCs and drive lineups they feed. Trip units, ZSI and arc-flash mitigation are set against the site's arc-flash and coordination studies.
Learn moreMedium-voltage equipment
Metal-clad switchgear for motors and incoming feeds
5 kV and 15 kV class metal-clad switchgear with vacuum circuit breakers serves incoming utility or generator feeds, transformer primaries and medium-voltage motor feeders. Arc-resistant construction and remote racking are common requests where the E-house doubles as a working space during operation.
Learn moreAutomation & controls
Generator, load-shed and transfer control
PLC- or relay-based generator paralleling, load shedding on loss of a source and main-tie-main transfer are engineered against the facility's operating cases, including islanded modes. Interface to the plant DCS or SCADA follows the owner's control philosophy, and protective actions remain governed by the protection scheme.
Learn moreMonitoring & analytics
Remote visibility for unattended sites
Relay events, breaker status, motor thermal data and E-house environmental alarms are collected and transmitted over Modbus TCP, DNP3 or IEC 61850 where applicable, including over cellular or satellite links for remote sites. Analytics flag abnormal motor and breaker behavior for the reliability team; any switching decision stays with operations.
Learn moreTypical equipment
What a oil & gas one-line usually contains
- Pressurized or purged E-houses and power distribution centers (PDCs) with integrated switchgear
- 15 kV class metal-clad switchgear with vacuum circuit breakers for incoming feeds and transformer primaries
- 5 kV class metal-clad switchgear for medium-voltage compressor and pump motor feeders
- Medium-voltage motor protection relays (49, 46, 87M, 50/51) coordinated with starting methods
- 480 V UL 1558 low-voltage power switchgear feeding MCCs and drive lineups
- Generator paralleling and load-shedding controls for islanded or weak-utility sites
- Arc-resistant construction and remote racking for occupied E-houses
- Remote monitoring gateways over cellular or satellite links
Codes and standards that commonly apply
Specifications govern
- Hazardous area classification and equipment location commonly follow NEC Articles 500 through 505 and API RP 500 or API RP 505; the area classification study and the owner's specifications govern where switchgear may be installed.
- Medium-voltage metal-clad switchgear is generally built to IEEE C37.20.2; low-voltage power switchgear is typically listed to UL 1558 and switchboards to UL 891. The equipment class the project specifies governs which applies.
- Motor specifications often reference IEEE 841 or API 541 and API 547; protection settings are developed from the motor data sheets and the coordination study rather than from generic defaults, and the project specification governs.
Questions we hear
Frequently asked
+Can switchgear be installed inside a Class I, Division 2 area?
Conventional switchgear is not rated for classified atmospheres, so the design approach is to place it in a pressurized or purged E-house, or in an area the classification study shows as unclassified. Purge and pressurization systems, gas detection and door interlocks then become part of the E-house design. The area classification study and the owner's HSE requirements govern.
+What does Apex include in an E-house or PDC scope?
The electrical scope typically covers medium- and low-voltage switchgear, transformers, MCCs, control panels, cable management and the monitoring and communications equipment, engineered together against one set of drawings. Building structure, HVAC, fire detection and pressurization are coordinated with the packaging partner or structural discipline the project assigns. Scope boundaries are defined in the proposal for each project.
+How do relay settings change when the site runs islanded on generators?
Generator sources supply far less fault current than a utility, so overcurrent elements set for utility-fed operation may not see a fault fast enough, or at all. The coordination study has to cover both source conditions, and relays may need setting groups that switch with the operating mode. Voltage-restrained overcurrent (51V) and directional elements are common tools in these schemes.
Related engineering resources
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Apex Power Distribution · ApexPower.ai
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