Y-Capacitor (Line-to-Ground): Capacitance Range 100pF to 10nF

Q: What is the difference between X and Y capacitors?

X capacitors are connected between line and neutral (line-to-line) and fail short, while Y capacitors are connected between line and ground (line-to-ground) and must fail open to prevent shock hazards. Y capacitors have stricter safety requirements.

Q: Why are Y capacitors critical for EMC compliance?

Y capacitors provide essential high-frequency grounding paths for electromagnetic interference without allowing dangerous leakage currents. They help meet conducted emissions limits (typically 150kHz-30MHz) in international EMC standards.

Q: What happens if a Y capacitor fails?

Properly rated Y capacitors are designed to fail open-circuit (not short-circuit) to maintain isolation between line voltage and ground. This prevents electric shock hazards but may reduce EMI filtering effectiveness.

Component Specifications

Definition

A specialized safety capacitor designed to suppress electromagnetic interference (EMI) by providing a low-impedance path between power lines and ground, specifically rated for line-to-ground applications where failure could create shock hazards. These capacitors must meet stringent safety standards due to their position in circuits where they bridge hazardous voltage to protective earth.

Working Principle

Operates by providing capacitive coupling between AC power lines and ground, shunting high-frequency noise currents to earth while blocking low-frequency power currents. The capacitor's dielectric withstands high voltage transients and maintains insulation resistance to prevent leakage currents from exceeding safety limits.

Materials

Metallized polypropylene or polyester film dielectric, epoxy resin encapsulation, copper or tin-plated steel leads, flame-retardant plastic case (typically UL94 V-0 rated)

Technical Parameters

Parameter	Typical range	Notes & selection driver
Tolerance	±20% typical
Safety Class	Y1, Y2, or Y4 per IEC 60384-14
Rated Voltage	250VAC to 440VAC
Leakage Current	<0.25mA typical at 250VAC
Capacitance Range	100pF to 10nF
Temperature Range	-40°C to +110°C
Dielectric Strength	≥4kV AC for 60 seconds
Insulation Resistance	≥10,000 MΩ

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

IEC 60384-14, UL 60384-14, EN 60384-14, IEC 60950-1, IEC 62368-1

Parent Products

This component is used in the following industrial products

Input Filter (EMC Filter)

An electromagnetic compatibility filter designed to suppress conducted electromagnetic interference (EMI) entering or leaving a device via the DC input power lines.

View Product Details

Engineering Analysis

Risks & Mitigation

Electric shock hazard if capacitor fails short
Excessive leakage current causing ground faults
Fire risk from dielectric breakdown
EMC non-compliance if incorrectly specified
Reduced equipment lifespan from improper derating

FMEA Triads

Trigger: Dielectric breakdown due to voltage transients
Failure: Capacitor short circuit creating shock hazard
Mitigation: Use Y1 or Y2 safety-rated capacitors with adequate voltage derating (typically 50% margin), implement surge protection devices upstream

Trigger: Thermal stress from high ambient temperatures
Failure: Increased leakage current, reduced capacitance, eventual open circuit
Mitigation: Select capacitors with appropriate temperature rating (+110°C minimum for industrial applications), ensure adequate ventilation, monitor operating temperature

Trigger: Mechanical vibration in industrial environments
Failure: Lead breakage, internal connection failure
Mitigation: Use capacitors with reinforced leads, proper PCB mounting with strain relief, vibration-resistant encapsulation

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Capacitance tolerance ±20% maximum, leakage current <0.25mA at rated voltage, dielectric withstand 4kV AC for 60 seconds minimum

Test Method

IEC 60384-14 safety tests: dielectric strength, insulation resistance, endurance (1000 hours at rated voltage and temperature), humidity resistance, flammability testing per UL94

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Y-Capacitor (Line-to-Ground)

Manufacturer profiles associated with Y-Capacitor (Line-to-Ground).

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Frequently Asked Questions

What is the difference between X and Y capacitors?