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Electrical Analog Instruments - Panel Board Types
UL 1437

3rd Edition dated April 29, 1998

Scope

1.1 These requirements cover electrical and electrically operated indicating and recording instruments of the analog type that are power ed only from the measured parameter and are intended for ordinary use in panel boards and the like.

1.2 These requirements cover direct -acting or indirect-acting instruments and accessories that may contain electronic devices.

1.3 These requirements cover instruments indicating quantities of electrical analogs including all of the following:

• Ammeters.
• Voltmeters.
• Wattmeters.
• Varmeters (reactive volt-ampere meters).
• Frequency meters.
• Power factor meters.
• Synchroscopes.

1.4 These requirements cover instruments constructed for special purposes such as, ultrasensitive d-c microammeters, high-resistance voltmeters, thermo-milliammeters, thermal voltmeters of the vacuum-couple type, and instruments with special and unusual ranges.

1.5 These requirements cover analog instruments that may be categorized according to use or principle of operation as follows:

• Use:
  • Panel Type, including edgewise.
  • Switchboard type, including edgewise.
• Principle of operation:
  • Electrodynamics.
  • Permanent-magnet moving coil.
  • Moving iron.
  • Thermocouple.
  • Rectifier.

1.6 These requirements also cover auxiliary equipment and accessories designed to be used with measuring instruments as indicated in 1.1 1.5.

1.7 These requirements do not cover:

• Indicating instruments provided with arrangements for curve drawing, contact making, and the like that derive the power for the functioning of these arrangements from an external source other than the measured parameter.
• Instruments that use active devices such as transistors , electron tubes, and the like for amplifying the electrical quantity measured, that require a power source other than the quantity measured for operation. An example of this is a battery-powered ohmmeter. This equipment is covered by the requirements for electrical and electronic measuring and testing equipment, UL 1244.

1.8 Instruments covered by these requirements are intended for use indoors or in sheltered (from the elements) locations, as follows:

a) Temperature 5 4 °C or 41 104 °F; instruments may occasionally be used for temporary or short periods at - 10 + 5 °C or 14 41 °F.

b) Altitude Up to 2200 meters (7218 feet).

c) Relative Humidity Up to 80 percent.

1.9 These requirements do not cover certain other properties of the instruments such as effectiveness, accuracy, or reliability.

1.10 Throughout this Standard the term "instrument" applies to analog indicating and recording instruments and their accessories as described in 1.1 1.6.

1.11 A product that contains features, characteristics, components, materials, or systems new or different from those covered by the requirements in this Standard, and that involves a risk of fire, electric shock, or injury to persons shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the acceptable level of safety as originally anticipated by the intent of this Standard. A product whose features, characteristics, components, materials, or systems conflict with specific requirements or provisions of this Standard cannot be judged to comply with this Standard. Where considered appropriate, revision of requirements shall be proposed and adopted in conformance with the methods employed for development, revision, and implementation of this Standard.