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Jewell FM Series – Frequency Meter

The pointer type frequency meters, FM 48/72/96/144 are housed in molded polycarbonate cases are suitable for the measurement of frequencies in the range of 45 to 450 Hz. For maximum accuracy, the essential measuring range is obtained by suppressing the unwanted frequency span. These instruments offer several advantages in switchboard and generating set panels. A number of meters can be mounted in a panel cut out (mosaic mounting). The front glass, bezel, and dial can be easily replaced.

Additional information


• Linear Scale
• Glass-filled polycarbonate housing
• Knife-edge pointer
• Easily replicable glass and bezel

Functional Principle

Frequencies are measured with a built-in electronic transducer and moving coil indicator. Moving coil movement has pivots of very high hardness. Movement is suspended between spring-loaded sapphire jewels. Movement is properly shielded and critically damped by eddy currents induced in coil former.

Case Options

• Antiglare glass front fascia
• Red, yellow, blue, or white bezel color
• Front adjustable on-site red index pointer
• 0° to 180° position of use available on request

Dial Options

• Blank dial with initial and end values marked
• Number or letter markings
• Basic divisions without numbering
• Red or green markings or bands



Case DetailsMolded square suitable for mounting in control switchgear panels and machinery consoles.
Case materialPolycarbonate, flame retardant, and drop proof per UL 94-V-0
Front FasciaGlass
Color of BezelBlack
Position of UseVertical
Panel FixingMounting clamps
MountingStackable in a single cutout
Panel Thickness≤25mm
TerminalsHexagon studs, M4, screws, and wire clamps, E3.


Measured QuantityFrequency
Input QuantityAlternating voltage in the sine waveform
Power Consumption<7Va
Overload CapacityAcc to IS: 1248/IEC 51
Continuously1.2 times rated voltage/current
Short Duration2 times rated voltage for 0.5 seconds: 9 overloads
2 times rated voltage for 5 seconds: 1 overloads
Enclosure Code (IEC 529)IP 52 - case cover
IP00 - terminals without back cover
IP20 - terminals with back cover
Insulation ClassGroup A according to VDE 0110
Rated Insulation Voltage660V
Proof Voltage2KV
Insulation Category300V CAT III
Insulation Resistance<50MΩ at 500 Vdc

Scale & Pointer

Scale Length41mm63mm97mm146mm
Scale CharacteristicsLinear
Scale DivisionCoarse - Fine
PointerKnife edge
Pointer Deflection0-90°


Climatic SuitabilityClimate category II as per IS:1248, IEC 60051
Climatic class III according to VDE/VDI 3540
Operating Temperature-10° to +55°C
Storage Temperature-25° to +65°C
Relative Humidity≥75% annual average, non-condensing
Shock Resistance15gn for pulse duration 11ms
Vibration Resistance10-55-10 Hz for amplification 0.15mm (1.5g at 50Hz)
Pollution Degree2

Applicable Standards

IS 2419
DIN IEC 61554
Nominal case and cutout dimensions for indicating electrical instruments
IS 1248
DIN 43802
Scale and pointer for electrical measuring instruments
IS 1248
DIN 43807
Connections and terminal markings for panel meters
DIN 46200
DIN 46282
Terminal bolts/leads
DIN 46282Clamp straps for connections
IS 9249
DIN 40050
Safety requirements and protective measures for electrical indicating.
VDE 0110
VDE 0410
IEC 529
IEC 1010
Instruments and their accessories.
IS 1248
IEC 51/DIN EN 60051
DIN 43701
Performance specifications for direct acting indicating analog electrical measuring instruments and their accessories.
IS 1248
IS 9000
VDE/VDI 3540
Environmental condition
DIN 43718Front frames for indicating measuring instruments principle dimensions
UL 94-V-0UL combustibility class
DIN 43701Technical conditions for delivery of electrical instruments
Is 1248/IEC 51
IS 9000
VDE 0411
IEC 61010
Mechanical strength (free-fall test, vibration test)

European Compliances

2004/108/ECEMC directive
2006/95/ECLow voltage directive
Amendment 93/68/EECFor CE marking



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