Motor load relay Type COSFI100V

Load- and Current monitor, active current with direction, over- and underload, cosfi

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Part number

AC 230 V

Product description


Motor load monitors monitor motors for overload and/ or underload. They are simply wired into the motor supply line and evaluate the phase angle between the voltage and the motor current or, optionally, the active current. That facilitates monitoring drive motors which enables, for instance, detecting a break in a V-belt or the blockage of a filter or valve.

As current directional relays, they monitor the direction of the flow of current to generators and whether current is being supplied or consumed.

The digital display and many adjustment facilities allow optimising the device for each task. The resolution of the measuring input is 0.1 A. When using a current transformer, multiply this by the transformer factor.

Cosfi application / Active current

  • V-belt monitoring
  • Fan monitoring
  • Pump monitoring
  • Conveying equipment (message if low is too low)
  • Stirrers
  • Wear monitoring
  • Tool wear
  • Load protection of motors, plants and drives

Current direction application

  • Warning or shutdown if a generator is consuming instead of supplying current
  • Optimizing of own consumption of energy in photovoltaic plants. Consumers can be switched on or off depending on power available. By measuring current at the feed point it can be detected, wheather there is enough power available to start heat pumps, cooling units or other consumers.
  • Limiting feeding-in power or preventing from feeding-in at plants for own generation of electricity

In an alternating current motor (inductive load), the current follows phase angle ϕ. If the load is decreasing, it increases so that the power factor (cosfi) decreases. This change of phase angle is a gauge of the change of the load on the motor. The COSFI 100 V motor load monitor is suitable for sinusoidal alternating current signals.

  • Digital displays for the power factor (cosfi) and active current
  • Inductive / capacitive load display
  • 2 limits / output relay
  • Each adjustable for min, max, or min/max
  • Monitoring of 2 x cosfi, 2 x active current or 1 x cosfi and 1 x active current
  • Current display scalable (converter factor)
  • Hysteresis and switching delay adjustable
  • Auto-reset or locked shutdown
  • Restarting attempts programmable 0…10
  • Auto-enable via current (> 0.2A) or via start signal (open bridges E1 - E2)
  • Auto-Enable (Strom) oder über Startsignal
  • Power-on delay can be adjusted 0…99s
  • Current input max. 10A through current transformer (sec. 5A) 999 A
  • Wire break in current measurement circuit
  • PTC thermistor input with short-circuit detection
  • Distributor housing for panel mounting 4TE, front-to-back size 55mm
  • Mounting on 35mm DIN EN 60715 standard rail or with screws (optional)
  • Accessory: Front mounting kit type ER4


Technical data

Rated supply voltage Us


AC 230 V, +10%/-15%, 3VA, 50 Hz


Power factor (cosϕ)




Hysteresis (cosϕ)




Nominal current of motor


0.2...10 A (higher currents with current-transformers)


Resolution active current


Current factor x 0.1 A


Overload capacity


10 A continuously, 15 A max. 3 s


Input Volatage L1-L2-L3


AC 100...400 V, 48...62 Hz




2 change-over contacts (co)


Type of contact


Type 2


Rated ambient
temperature range





Dimensions (h x w x d)


Design V4: 90 x 70 x 58 mm, mounting height 55 mm




on rail 35 mm according to EN 60 715 or with screws M4 (option)


Protection housing/terminals


IP 30 / IP 20




approx. 300 g




Operating manual