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CAN CSA C50064-99 (2016) – Metal-Oxide Surge Arresters for AC Systems: Technical Requirements and Compliance
A comprehensive overview of the Canadian adoption of IEC 60099-4 covering scope, design specifications, testing regimens, and certification pathways for metal-oxide surge arresters without gaps.
1. Scope and Field of Application
CAN CSA C50064-99 (2016) is the Canadian national adoption of IEC 60099-4:1998, applicable to metal-oxide surge arresters without gaps used to limit overvoltages on alternating current power systems. This standard covers arresters designed for system voltages from 1 kV up to 800 kV and above, and applies to both distribution and transmission class devices.
The document establishes uniform requirements for construction, electrical characteristics, test methods, and performance criteria. It replaces earlier editions and harmonizes with current international practices, ensuring that certified arresters provide reliable protection against lightning and switching surges while maintaining long-term stability under normal operating conditions.
Tip: When selecting a surge arrester for a specific application always refer to the classification table in Clause 4 of the standard. It provides guidance on nominal discharge current and rated voltage ranges suitable for different system configurations.
2. Technical Requirements
2.1 Classification
Arresters are classified according to their nominal discharge current (In) and rated voltage (Ur). The standard defines five classes: 1 kA, 2.5 kA, 5 kA, 10 kA, and 20 kA. Each class corresponds to a specific energy absorption capability and application type, from secondary protection to heavy-duty transmission line protection.
2.2 Construction and Materials
Metal-oxide varistor (MOV) blocks must be free of cracks, voids, and contamination. The housing can be porcelain, silicone rubber, or composite material, and must provide adequate creepage distance and withstand environmental stresses. Sealing systems must prevent moisture ingress over the entire service life. All components must be designed to operate in ambient temperatures from –40 °C to +40 °C unless otherwise specified.
2.3 Electrical Characteristics
Key parameters include:
- Reference voltage (Uref): measured at a specified resistive current (usually 1 mA peak).
- Residual voltage (Ures): maximum voltage across the arrester when discharging a nominal impulse current (8/20 µs).
- Energy absorption rating: defined by the thermal energy (kJ/kV of Ur) the arrester can absorb during a standard operating duty test.
- Long-duration current withstand: ability to pass rectangular-wave impulses without thermal runaway.
| Classification | Nominal Discharge Current In (kA) | Rated Voltage Ur Range (kV) | Typical Energy Class (kJ/kV) | Application |
|---|---|---|---|---|
| Light Duty | 1 – 2.5 | 3 – 36 | 1 – 2 | Secondary distribution, cable protection |
| Standard Duty | 5 | 36 – 145 | 3 – 5 | Substations, overhead lines |
| Heavy Duty | 10 | 145 – 362 | 6 – 10 | Transmission lines, industrial networks |
| Extra Heavy Duty | 20 | 362 – 800+ | 12 – 15 | EHV systems, series compensation |
3. Testing Regimens
3.1 Type Tests
Type tests are performed once on a representative prototype to validate the design. They include:
- Insulating housing test: dry and wet power-frequency voltage withstand and lightning impulse withstand.
- Residual voltage test: at nominal discharge current and at high current (65 kA – 100 kA).
- Long-duration current impulse withstand test: two series of 20 rectangular-wave impulses at specified energy levels.
- Operating duty test: pre-conditioning with high-current impulses followed by power-frequency voltage application to verify thermal stability.
- Sealing and mechanical tests: water immersion, internal pressure withstand, mechanical bending and torsion.
3.2 Routine Tests
Each production unit must pass routine tests to ensure consistency:
- Reference voltage measurement at 1 mA d.c.
- Leakage current test at 75% of reference voltage.
- Partial discharge measurement (acceptance: < 10 pC).
- Internal overpressure relief test (if specified).
Caution: Routine tests should be performed immediately after assembly and before attaching the pressure relief device. Test noise from external sources can affect partial discharge readings – ensure a shielded environment.
3.3 Acceptance Criteria
For sample tests (e.g., from a batch), the standard provides allowable tolerances. If a sample fails, double the number of units must be re-tested. Failure of any unit leads to rejection of the entire batch unless the manufacturer demonstrates corrective action.
4. Implementation and Compliance Notes
4.1 Certification in Canada
Compliance with CAN CSA C50064-99 (2016) is required by most provincial electrical codes for surge arresters installed in utility and industrial systems. Certification is typically performed by accredited bodies such as CSA Group or other SCC-accredited labs. The certificate must reference the standard edition and reaffirmation date (2016).
4.2 Marking and Documentation
Each arrester must bear a durable nameplate showing:
- Manufacturer’s name or trademark
- Type designation and serial number
- Rated voltage (Ur) in kV
- Nominal discharge current (In) in kA
- Year of manufacture
- Symbol of certification body (e.g., CSA mark)
Installation manuals and test reports must be provided upon request.
4.3 Differences from International Base
CAN CSA C50064-99 (2016) is an identical adoption of IEC 60099-4:1998. No technical deviations are introduced. However, Canadian users may need to consider additional requirements from CSA C22.2 No. 0.4 if the arrester is part of a certified assembly.
Key Benefit: By specifying arresters that comply with CAN CSA C50064-99, engineers ensure that overvoltage protection equipment meets high reliability and safety expectations, reducing downtime and extending asset life.
4.4 Maintenance of Certification
Manufacturers must maintain quality assurance per ISO 9001 or equivalent. The certification body may conduct periodic factory inspections and re-testing. Any change in design or material requires re-qualification of type tests.
Frequently Asked Questions
Q: Is CAN CSA C50064-99 (2016) completely identical to IEC 60099-4:1998?
A: Yes, this is an identical adoption. Only editorial changes have been made to reflect Canadian metric usage and referencing of related CSA standards. The technical content is unchanged.
A: Yes, this is an identical adoption. Only editorial changes have been made to reflect Canadian metric usage and referencing of related CSA standards. The technical content is unchanged.
Q: What routine tests are mandatory for each surge arrester?
A: Every unit must pass reference voltage, leakage current, and partial discharge measurements. Additional tests (e.g., pressure relief) are required when the design relies on such features.
A: Every unit must pass reference voltage, leakage current, and partial discharge measurements. Additional tests (e.g., pressure relief) are required when the design relies on such features.
Q: Can an arrester certified under IEC 60099-4 be used in Canada without re-test?
A: Typically not. The product must be certified by an SCC-accredited laboratory to CAN CSA C50064-99 (2016) to satisfy Canadian code requirements. However, if the certification body has a mutual recognition agreement, testing to the IEC standard may be accepted with supplementary review.
A: Typically not. The product must be certified by an SCC-accredited laboratory to CAN CSA C50064-99 (2016) to satisfy Canadian code requirements. However, if the certification body has a mutual recognition agreement, testing to the IEC standard may be accepted with supplementary review.
Q: How often is this standard updated?
A: CSA standards are normally reaffirmed every five years. The 2016 reaffirmation confirmed no technical changes. A new edition based on IEC 60099-4:2014 is currently under ballot. Users should check the CSA website for the latest version.
A: CSA standards are normally reaffirmed every five years. The 2016 reaffirmation confirmed no technical changes. A new edition based on IEC 60099-4:2014 is currently under ballot. Users should check the CSA website for the latest version.
Article prepared for technical reference purposes. Last updated 2026.