601575 - 601 Series – Three-Phase Voltage & Frequency Monitor Series

Series: 601 Series – Three-Phase Voltage & Frequency Monitor
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The Model 601 is a fully-programmable voltage monitor designed to protect 3-phase motors. It can be used as a stand-alone product or networked with an RM-1000, RM-2000, PLC, computer or SCADA system.


When a harmful condition is detected, the 601’s output relay is deactivated after the specified trip delay. The output relay reactivates after power line conditions return to an acceptable level for the programmed restart delay (RD2).


Eleven (11) setpoints are viewable with the 3-digit LED display or from a networked device:

    low voltage
      high voltage
        voltage unbalance
          low frequency
            high frequency
              RS485 address
                trip delay for voltage/frequency faults
                  trip delay for single-phase faults
                    rapid-cycle timer (RD1)
                      restart delay after all faults (RD2)
                        type of restart after all faults (manual or automatic)

                        Six (6) parameters are viewable while the motor is running:

                          L1-L2 voltage
                            L2-L3 voltage
                              L1-L3 voltage
                                average voltage
                                  voltage unbalance (%)
                                    voltage frequency (%)


                                    When used with the RS485MS-2W communications module, the 601 can communicate with most Modbus RTU master devices. Voltage conditions can be monitored and setpoints can be changed remotely using Solutions software, an RM-1000, RM-2000 or other device.

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Product Literature

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Call +1 800-832-3873 or email us at relays@littelfuse.com 

Property (Mouseover for details) Value
Input Voltage (V) 500 - 600 Vac
Maximum Input Power 5
Input AC Line Frequency (Hz) 50 / 60
Output Load Rating (VA) Pilot Duty: 480 VA @ 240 Vac; General Purpose: 10 A @ 240 Vac
Timing Accuracy (%) 5% ±1 s
Rapid Cycle Timer (s) 0; 2 - 500 s
Restart Delay Range Restart Delay After All Faults: 2 - 500 s
Repeat Accuracy (%) Voltage: ±0.5%
Trip Delay Range Voltage/Unbalance/Frequency faults/single-Phase faults: 1 - 50 s
Overvoltage Reset Voltage (%) 97% of HV Setting
Undervoltage Reset Voltage (%) 103% of LV Setting
Voltage Unbalance Reset (%) UB Setting -1%
Voltage Accuracy (%) ±1%
Over/Under Frequency (%) Low: 35 Hz - HF setting; High: LF setting - 75 Hz
Protection Class IP20; NEMA 1 (finger safe)
Address A01 - A99
Termination Type Torque: 7 in-lbs
Mounting Method Surface mount (4 - #8 screws) or DIN rail mount
Operating Temperature -20° to 70°C (-4° to 158°F)
Storage Temperature (F/C) -40° to 80°C (-40° to 176°F)
Humidity 95% non-condensing per IEC 68-2-3
Dimensions 3.05 H x 3.85 W x 5.05 D in. (77.5 x 97.8 x 128.3 mm)
Weight (lbs/g) 0 Kg
Check Stock Yes

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