UL 497B
UL 497B
UL 497B provides requirements for protectors used in communication and fire alarm
circuits. This standard does not cover devices for primary protection or protection devices
used on telephone lines. SIDACtor devices are components recognized in accordance with
UL 497B under UL file number E133083.
Construction and Performance Requirements
The “Construction” section covers the following requirements:
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General
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Corrosion Protection
Field-wiring Connections
Components
Spacing
Fuses
The “Performance” section covers the following requirements:
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General
Strike Voltage Breakdown
Endurance Conditioning
Temperature Test
Dielectric Voltage-withstand Test
Vibration Conditioning
Jarring Test
Discharge Test
Repeated Discharge Test
Polymeric Materials Test
High Temperature Test
Marking
Performance Requirements Specific to SIDACtor Devices
1. Strike Voltage Breakdown Test — Protectors are required to break down within the
manufacturer’s specified breakdown range or within 10% of a nominal single breakdown
voltage rating. (Figure 4.12)
2. Endurance Conditioning — Protectors are subjected to 50 impulse cycles. Each cycle is
a 1000 V peak, 10 A, 10x1000 µs pulse. Pulses are applied in one polarity at 10-second
intervals and then repeated in the opposite polarity.
3. Variable Ambient Conditioning — Protectors must comply with the strike voltage
requirements after being subjected to an ambient temperature of 0 °C for four hours and
again after being subjected to an ambient temperature of 49 °C for an additional four
hours.
4. Discharge Test — Protectors must comply with strike voltage requirements after being
subjected to five successive discharges from a 2 µF capacitor charged to 1000 V dc.
(Figure 4.13)
5. Repeated Discharge Test — Protectors must not break down at a voltage higher than the
manufacturer’s maximum rated breakdown voltage nor lower than rated stand-off
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© 2002 Teccor Electronics
SIDACtor Data Book and Design Guide
®
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