MCC Panels

Surge Protection Devices (SPD) in Power Control Center (PCC)

Surge Protection Devices (SPD) selection, integration, and best practices for Power Control Center (PCC) assemblies compliant with IEC 61439.

Surge Protection Devices (SPD) in Power Control Center (PCC)

Overview

Surge Protection Devices (SPD) in Power Control Center (PCC) assemblies are essential for protecting busbar systems, feeder circuits, control power, metering, PLCs, and communication networks against transient overvoltages caused by lightning, switching operations, and utility disturbances. In a PCC, SPDs are typically coordinated as Type 1, Type 2, or combined Type 1+2 devices at the incoming section, with additional Type 2 or Type 3 protection applied downstream for sensitive control and automation loads. Selection must align with the supply arrangement, earthing system, and prospective lightning current, while also respecting the assembly design principles of IEC 61439-1 and IEC 61439-2. For industrial sites, the SPD coordination philosophy is usually paired with air circuit breakers (ACBs), molded-case circuit breakers (MCCBs), protection relays, metering, and busbar systems rated from 630 A up to 6300 A or higher depending on the PCC architecture. Engineering of SPD integration in a PCC requires attention to impulse current rating, maximum continuous operating voltage (Uc), voltage protection level (Up), short-circuit current rating with the upstream protective device, and the backup protection coordination specified by the manufacturer. In practice, SPDs are selected to withstand the panel’s prospective short-circuit current, often in assemblies with SCCR or conditional short-circuit ratings validated against the main incomer device. Compact modular SPDs with remote indication contacts are favored for modern panels because they support SCADA, BMS, and PLC monitoring through dry contacts or communication gateways. Where harmonic loads, VFDs, soft starters, and capacitor banks are present, the SPD arrangement should be reviewed for transient sources and possible coupling effects across feeder sections. Thermal performance is another critical factor in PCC layouts. IEC 61439 temperature-rise limits must be verified because SPDs dissipate heat during normal operation and after surge events. This is especially important in densely populated sections that also contain ACBs, MCCBs, motor feeder starters, control relays, and multifunction meters. Adequate spacing, terminal selection, and enclosure ventilation must be considered, particularly in floor-standing PCCs with high ingress protection requirements and elevated ambient temperatures. For indoor switchrooms, form-of-separation practices such as Form 3b or Form 4 can help localize maintenance while preserving segregation between incomers, bus couplers, and outgoing feeders. For specialty applications, SPD selection may also be influenced by IEC 61439-3 auxiliary distribution boards, IEC 61439-6 busbar trunking interfaces, and the use of explosion-risk equipment in related facilities where IEC 60079 or arc containment expectations per IEC/TR 61641 apply. In oil and gas, water treatment, data centers, commercial towers, and manufacturing plants, a properly engineered SPD scheme reduces downtime, protects expensive automation hardware, and improves overall power quality resilience. Patrion designs PCC assemblies in Turkey with SPD integration tailored to the incoming fault level, earthing method, and operational continuity requirements of the project, ensuring compliant, maintainable, and communication-ready power distribution solutions.

Key Features

  • Surge Protection Devices (SPD) rated for Power Control Center (PCC) operating conditions
  • IEC 61439 compliant integration and coordination
  • Thermal management within panel enclosure limits
  • Communication-ready for SCADA/BMS integration
  • Coordination with upstream and downstream protection devices

Specifications

PropertyValue
Panel TypePower Control Center (PCC)
ComponentSurge Protection Devices (SPD)
StandardIEC 61439-2
IntegrationType-tested coordination

Other Components for Power Control Center (PCC)

Air Circuit Breakers (ACB)

Main incoming/outgoing protection, 630A–6300A, draw-out mounting

Moulded Case Circuit Breakers (MCCB)

Branch protection 16A–1600A, thermal-magnetic or electronic trip

Busbar Systems

Copper/aluminum busbars, busbar supports, tap-off units

Metering & Power Analyzers

Energy meters, power quality analyzers, CT/VT, communication gateways

Protection Relays

Overcurrent, earth fault, differential, generator protection relays

Other Panels Using Surge Protection Devices (SPD)

Main Distribution Board (MDB)

Primary power distribution from transformer to sub-circuits. Rated up to 6300A. Houses main incoming breaker, bus-section, and outgoing feeders.

Variable Frequency Drive (VFD) Panel

Enclosed VFD assemblies with input protection, line reactors, EMC filters, output reactors, and bypass options.

Metering & Monitoring Panel

Energy metering, power quality analysis, and multi-circuit monitoring with communication gateways.

Lighting Distribution Board

Final distribution for lighting and small power. MCB/RCBO-based with DALI or KNX integration options.

Busbar Trunking System (BTS)

Prefabricated busbar distribution per IEC 61439-6. Sandwich or air-insulated, aluminum or copper.

Custom Engineered Panel

Bespoke panel assemblies for non-standard requirements — special ratings, unusual form factors, multi-function combinations.

DC Distribution Panel

DC power distribution for battery systems, solar installations, telecom, and UPS applications. MCCB/fuse-based DC protection.

Frequently Asked Questions

For a PCC incomer, the choice depends on the exposure level and lightning current risk. Type 1 SPDs are typically used where lightning current may enter the installation, especially at service entrances with external LPS or overhead supplies. Type 2 SPDs are common in most industrial PCCs for switching surges and residual transient suppression. In many cases, a coordinated Type 1+2 device is preferred at the main incoming section. Selection should follow IEC 61643 device data in coordination with IEC 61439-1/2 panel design criteria, including Uc, Up, and the upstream backup protection device. The final arrangement must also match the earthing system, whether TN-S, TN-C-S, TT, or IT.
SPD short-circuit coordination is achieved by matching the device’s backup fuse or breaker requirements with the upstream protective device, typically an ACB or MCCB in the PCC incomer. The SPD manufacturer publishes a maximum prospective short-circuit current and the minimum backup protection rating required to safely disconnect a failed unit. In IEC 61439 assemblies, this coordination must be checked against the panel’s short-circuit withstand capability and the feeder protection scheme. For high-fault industrial boards, this often means selecting SPDs with integrated fusing or pairing them with dedicated MCBs or fused disconnectors. Proper coordination prevents nuisance tripping and protects the busbar system.
SPDs are normally installed as close as possible to the incoming power terminals and bonded to the main earthing bar with the shortest practical conductor length. In a PCC, the main SPD is usually located adjacent to the ACB or incoming MCCB to minimize let-through voltage. Secondary SPDs may be installed in outgoing sections feeding sensitive loads such as PLCs, SCADA panels, VFDs, soft starters, UPS systems, or metering circuits. IEC 61439 design practice emphasizes compact routing, controlled conductor length, and clear segregation from control wiring to reduce inductive coupling during surge events. Good installation geometry is as important as device rating.
The primary panel standard is IEC 61439-1 and IEC 61439-2 for low-voltage switchgear and controlgear assemblies, which governs temperature rise, short-circuit withstand, clearances, and internal separation. SPD product performance is normally evaluated against IEC 61643 series requirements for surge protective devices. If the panel includes downstream auxiliary distribution or special enclosures, IEC 61439-3 and IEC 61439-6 may also be relevant. In projects with hazardous atmospheres or arc-risk requirements, IEC 60079 and IEC/TR 61641 can influence enclosure selection and internal arc performance. The SPD itself must be selected as part of a verified assembly, not as a standalone component.
Yes. Most modern SPDs offer remote alarm contacts, status indicators, and in some models communication modules for integration with SCADA or BMS platforms. In a PCC, this is useful for predictive maintenance because the panel operator can monitor normal status, end-of-life indication, and fault alarms from the control room. Integration should be engineered so that the dry contact or communication signal is routed through the low-voltage control section with proper segregation from power wiring. This supports maintenance planning and reduces downtime. For critical facilities such as hospitals, data centers, and process plants, remote SPD monitoring is often specified as part of the panel’s intelligent architecture.
VFDs and soft starters introduce switching transients, harmonic currents, and sensitive semiconductor electronics that can be affected by surges and voltage distortion. In a PCC supplying these loads, SPD selection should consider the downstream protection level and the possibility of repeated transient stress. Type 2 SPDs are commonly used on feeders supplying drives, while Type 3 protection may be added near sensitive electronics. The installation should also account for cable length, EMC practices, and the drive manufacturer’s recommendations. Coordination with motor control centers, MCCBs, and control transformers is important to prevent unwanted interaction and maintain compliance with IEC 61439 temperature-rise and functional separation principles.
SPDs add heat dissipation to the enclosure, especially after surge events or during continuous leakage current operation. In a PCC, this must be considered alongside ACBs, MCCBs, metering devices, relays, and cable density. IEC 61439 requires the verified temperature rise of the assembly to remain within limits for conductors, terminals, and mounted components. Practical design measures include allocating ventilation space, avoiding direct proximity to heat-sensitive electronics, using plinth or top-exhaust arrangements where appropriate, and selecting SPDs with low standby losses. Thermal margin becomes especially important in high-current boards, compact enclosures, and installations in hot climates.
A typical industrial PCC uses a coordinated cascade: a Type 1 or Type 1+2 SPD at the main incomer, Type 2 SPDs on major outgoing feeder sections, and Type 3 devices near very sensitive loads such as PLC cabinets, network switches, or instrumentation panels. This layered approach improves voltage limitation and reduces stress on downstream equipment. The configuration is chosen according to the site’s exposure level, cable runs, and load criticality. In a well-designed PCC, the SPD system is coordinated with the incoming ACB, outgoing MCCBs, busbar rating, and the verified short-circuit performance of the assembly under IEC 61439-2. This is the most reliable architecture for industrial power distribution.

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