Product Catalog

M.C. Miller Cronos GPS

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M.C. Miller Cronos GPS available in both 40 and 100 amp models.

Available in both 40 Amp and 100 Amp models







  • Rugged M. C. Miller Co. design, highly reliable, easy to operate and very competitively-priced.
  • Precision clock-timing even with an intermittent view of the GPS satellites.
  • Two years of continuous (current interruption) operation on a single set of replaceable "D" cell batteries - no need to recharge the unit every few days
    Note: Although the batteries are the same physical size as regular “D” cell batteries, they are 3.6V, rather than the standard 1.5V “D” cells. The 3.6V “D” cells (19Ah capacity) are available from M. C. Miller (Cat. #BAT0064)
  • Easy to program via a PC or can "quick select" via the keypad
  • Available in 100A relay (external relay) and 40A relay (internal relay) models. Both relays are rated at 120V AC/DC
  • Solid-state (non-polarity dependent) relay - no unit orientation or polarity concerns
  • Only 1mV dropped across the relay per Amp - both small and large currents can be interrupted
  • Fully-automated current-interruption programs can be started in the field with the push of a single button.



Maximum Current:
100 Amps at 120V (12,000 watts) external relay
40 Amps at 120V (4,800 watts) internal relay

Maximum Working Voltage:
170V DC (either polarity), 120Vrms (50/60Hz).

Voltage Drop:
1mV per Amp Suitable for interrupting low Voltage bonds and anodes.

Overload Protection:
75kW(10/100µs); 500kW(8/20µs) 1.2kA peak @ clamp voltage. Auto thermal shutdown at 105oC.

Isolation to ground:
2,000 Volts

Setup Options:
  • On/Off 0.1 to 99 sec. 0.1 sec increments
  • Start and stop date and time
  • Begin cycle with relay open or closed
  • Close relay at end of work day
  • Start cycle at beginning of work day
  • Switching offsets ±500ms (both On-to-Off and Off-to-On) – allows for use of other relay types.

Power Consumption:
  • Runs on 2 "D" Cell batteries (3.6V, 19Ah)
  • Battery-life depends on programmable settings - 2 years continuous operation typical on default settings.
Time Standards:
UTC (default) or GPS; Synchronization @ 00.00 (default) or @ start time; Local –Offset; user defined to ensure consistency

Clock/Interruption Accuracy:
  • 1ms max. deviation with satellites in view
  • 0.5 ms per hour without satellites in view
  • Reacquires precision time when satellites return to view
Temperature compensated range:
-40oC to +85oC.

Temperature Range:
  • Relay Operation: -40oC to +85°C
  • LCD Operation: -20oC to +70°C
Multiple Unit Programming:
Cronos PC software allows personal settings to be created and saved for future download to Cronos units, or a "master" Cronos unit can be used to automatically program other Cronos units.

  • 40A Model: 9"L, 11"W, 6"D (15.4 lbs)
  • 100A Model:
    Control Unit: 9"L, 11"W, 3"D (5.6 lbs)
    Relay Unit: 13.5"L, 7"W, 4"D (19.4 lbs)
Ships with the following:
  • 6 feet of ultra flexible #2 cable
  • Windows setup software
  • PC to Cronos RS-232 cable