CAN/CSA C61000-3-11-06: Limitation of Voltage Changes, Fluctuations, and Flicker for Equipment with Conditional Connection

Scope and Purpose

CAN/CSA C61000-3-11-06 is the Canadian adoption of the international standard IEC 61000-3-11:2004, titled Electromagnetic compatibility (EMC) – Part 3-11: Limits – Limitation of voltage changes, voltage fluctuations and flicker in public low-voltage supply systems – Equipment with rated current ≤ 75 A and subject to conditional connection. This standard forms part of the series of EMC standards developed by the International Electrotechnical Commission (IEC) and adopted under the standards system of the Canadian Standards Association (CSA).

The standard specifies emission limits for voltage changes, voltage fluctuations, and flicker produced by electrical and electronic equipment that has a rated input current up to and including 75 A per phase and is intended to be connected to public low-voltage alternating current distribution systems. Conditional connection refers to cases where the equipment cannot meet the general limits of the companion standard IEC 61000-3-3 (or its Canadian adoption CAN/CSA C61000-3-3) under normal installation conditions, but may still be permitted to be connected if specific conditions regarding the supply network’s short-circuit capacity are satisfied.

Important: CAN/CSA C61000-3-11-06 applies only to equipment that is subject to conditional connection. Equipment that meets the limits of CAN/CSA C61000-3-3 without additional conditions is not within the scope of this standard.

The purpose of the standard is to ensure that the voltage quality on public low-voltage networks is not degraded to an unacceptable level, particularly with respect to visible flicker of lighting, which is the most perceptible effect of rapid voltage fluctuations. By defining limits and connection conditions, the standard helps network operators manage the cumulative effect of fluctuating loads while allowing innovative equipment designs that may otherwise exceed generic emission limits.

Technical Requirements and Emission Limits

The standard defines limits for three key flicker and voltage change parameters assessed at the point of common coupling (PCC):

Short-term flicker severity (P_st) measured over a 10-minute interval.
Long-term flicker severity (P_lt) derived from a sequence of P_st values over a 2-hour period.
Relative steady-state voltage change (d_c) and maximum relative voltage change (d_max).

Unlike the unconditional limits for equipment with rated current ≤ 16 A (covered by CAN/CSA C61000-3-3), CAN/CSA C61000-3-11-06 allows higher emission levels provided that the equipment is connected only to supply points where the three-phase short-circuit power (S_{sc_eq}) is sufficiently high relative to the equipment’s apparent power (S_equip). The permissible limits are given as functions of the short-circuit power ratio k = S_{sc_eq} / S_equip.

Parameter	Limit	Application Condition
Short-term flicker severity (P_st)	≤ 1.0	For any assessment period of 10 minutes; k must be ≥ 33
Long-term flicker severity (P_lt)	≤ 0.65	Derived from 12 consecutive P_st values; condition as above
Maximum relative voltage change (d_max)	≤ 4 % (or ≤ 6 % for changes occurring less than once per minute)	At the PCC, assuming minimum short-circuit power specified by the manufacturer
Relative steady-state voltage change (d_c)	≤ 3 %	Under normal operation; allowed up to 4 % if the change occurs less frequently

Tip: The ratio k is critical. Manufacturers must declare the minimum required short-circuit power at the PCC in the equipment documentation. The installer or end user is responsible for verifying that the actual network short‑circuit power meets or exceeds this value.

The standard also provides test methods for measuring the flicker emission of equipment. The measurement setup uses a flickermeter conforming to IEC 61000-4-15 and is performed under a reference impedance that represents the supply network. For conditional connection assessments, the reference impedance may be adjusted to correspond to the declared minimum short-circuit capacity.

Implementation Highlights for Manufacturers and Utilities

For Equipment Manufacturers

Design equipment to minimize intrinsic voltage fluctuations, for example by using soft-start circuits or power factor correction.
Determine the emission levels (P_st, P_lt, d_max, d_c) by testing according to Annex A of the standard.
If the emissions exceed the limits of CAN/CSA C61000-3-3 (applicable to general equipment), the manufacturer must specify in the user manual: the emission values, the minimum short-circuit power required at the PCC, and the condition that connection is subject to agreement with the supply authority.
Ensure that the equipment’s rated current per phase does not exceed 75 A.

For Utility Engineers and Installation Assessors

Review the equipment documentation to confirm the declared minimum short-circuit power and maximum emission levels.
Verify that the actual short-circuit power at the proposed point of connection is ≥ the declared minimum. This may require calculation based on transformer rating, line impedance, and parallel load contributions.
Consider the cumulative effect of multiple fluctuating loads connected to the same PCC. The standard does not specify summation methods, but guidance can be found in IEC 61000-3-13 or other relevant technical reports.
Maintain records of conditional connections for network quality management.

Good Practice: Early dialogue between manufacturer and utility during the product development stage can help avoid last-minute compliance issues. A pre-compliance assessment using the simplified method in Annex B of the standard can be performed even before a formal flicker test is done.

Compliance and Verification Notes

Compliance with CAN/CSA C61000-3-11-06 is typically verified by type testing. The manufacturer must submit representative samples to an accredited laboratory that can perform flicker measurements using the standard’s test setup. The key elements of compliance include:

Test report: Shall include all emission parameters and the declared minimum short-circuit power.
Marking: The equipment must be marked with a warning indicating conditional connection requirement, along with the reference to CAN/CSA C61000-3-11-06 (or IEC 61000-3-11).
User documentation: Must contain the minimum required short-circuit power and explicit instructions to obtain utility agreement before final connection.
Periodic audits: Some certification bodies may require periodic factory inspections or re-testing if design changes affect the flicker characteristics.

It is important to note that CAN/CSA C61000-3-11-06 is referenced in the Canadian Electrical Code (CEC) and by local electricity distributors as part of their connection policies. Failure to comply can result in refusal of connection or disconnection until corrective measures are taken.

Non-Compliance Risk: Connecting equipment subject to conditional connection without prior approval may lead to excessive flicker complaints, penalties, and liability for damage to sensitive equipment. Always secure written agreement from the supply authority before commissioning.

The standard also gives guidance for the case where multiple units of the same type are installed at the same site. The cumulative short-circuit power demand scales with the number of units, and the minimum required short-circuit power must be adjusted accordingly.

Frequently Asked Questions

Q: What is the difference between CAN/CSA C61000-3-11-06 and CAN/CSA C61000-3-3?
A: CAN/CSA C61000-3-3 applies to equipment with rated current ≤ 16 A that must meet unconditional flicker and voltage change limits. CAN/CSA C61000-3-11-06 is for equipment with rated current ≤ 75 A that exceeds those limits, but may still be connected if the supply point has sufficient short‑circuit capacity and a conditional connection agreement is obtained from the utility.

Q: How do I determine the minimum short-circuit power required for my equipment?
A: The required minimum short-circuit power at the PCC is derived from the measured emission levels of your equipment. The standard provides a calculation method in Annex A: for a given P_st value, the minimum short-circuit power is (P_st × S_equip) / P_st,limit. For P_st limit of 1.0, the minimum S_sc is simply S_equip × P_st. However, additional constraints apply for voltage changes and flicker. The manufacturer should compute and specify the worst‑case required value.

Q: Can equipment that meets CAN/CSA C61000-3-3 still be tested under CAN/CSA C61000-3-11-06?
A: No. The scope of CAN/CSA C61000-3-11-06 explicitly excludes equipment that already complies with the limits of CAN/CSA C61000-3-3 without any additional conditions. Testing under this standard is intended only for equipment that does not meet unconditional limits and requires a conditional connection arrangement.

Q: Is CAN/CSA C61000-3-11-06 still current in 2026?
A: As of 2026, CAN/CSA C61000-3-11-06 remains the published Canadian adoption of IEC 61000-3-11:2004. Users should check with the CSA Group or their local regulatory authority for any amendments, revisions, or newer editions that may have been issued. The standard may also be complemented by other EMC standards in the CAN/CSA C61000 series.

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