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3 Phase Monitoring Relay MMR17-PDF-A230-108

  • MA function (asymmetry)
  • MS function (rotation)
  • No contactor monitoring
  • Adjustable asymmetry threshold 30…70V
  • Adjustable detection time 1…6s
  • Adjustable recovery time same as detection time.
  • 1NO/NC 8A contact arrangement
  • Installation design DIN 35mm
  • 17.5mm width

Time relay MMR17-PDF-A230-108 is designed to protect loads (inductive motors) against voltage asymmetry and wrong phase rotation in 3 phase networks. If the assymetry voltage above the adjustable threshold 30…70V or wrong rotation lasts longer than detection time, the output relay is switched off. The relay can be recovered to normal operation if asymmetry drops below the threshold and the rotation is correct.

Time function available in the MMR17-PDF-A230-108 relay:

Functions – MA (asymmetry) – Asymmetry monitoring. As soon as the asymmetry exceeds the value at the Uas – regulator, the set interval of the tripping delay (DELAY) begins. After the interval has expired the output relay R switches into off-position (yellow LED not illuminated).
Function – MS (sequence) – Phase sequence monitoring. When all the phases are connected in the correct sequence and the measured asymmetry is less than the set value, the output relay switches into on-position (yellow LED illuminated). When the phase sequence changes, the output relay switches into off‑position (yellow LED not illuminated).


Front Panel


Version MMR17-PDF-A230-108
Output Circuit
Contact arrangement 1NO/NC
Rated switching current In AC1 – 8A/250V AC
DC1 – 8A/24V DC
Maximum continuous current 8A
Switching load range AC1 2 000VA
Rated/maximum contact voltage 250/400V AC
Contact resistance ≤ 100mΩ
Maximum switching frequency
600 cycles/h
Input Circuit
Supply voltage Un 3x 400/250V AC
0,8…1,1Un (184…253V)
Phase power supply of control circuit L1
Rated consumption ≤ 8VA
Rated frequency 47…63Hz
Rated surge voltage 1 000V
Insulation rated voltage 400V AC
Rated surge voltage 4 000V (1,2/50μs)
Overvoltage category III
Pollution degree
Dielectric strength input-output 4 000V AC
Dielectric strength open contact 1 000V AC
Measuring circuit
Regulation asymmetry range Uasym
Functions MA, MS
Setting accuracy
≤ 5%
Repeatability ≤ 2%
Time Module
Time off delay
Adjustable 1…6s
Recovery time
Reset time
≤ 500ms
Timing accuracy
General data
Electrical life AC1 at 1000VA resistive load
≥ 150 000
Mechanical life
≥ 10 000 000
Dimensions (L x W x H)/Weight
90 x 17.5 x 66mm / 53g
Ambient temperature
Storage temperature -40…+70°C
IP rating IP20
Relative humidity
Shock resistance 15g
Vibration Resistance 0.35mm (10…55Hz)
LED indicator 2 LED

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Declaration of conformity CE


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Monitoring relays ensures reliable system protection against demage.

It is used to secure loads (eg. motors) from the voltage unbalance, incorrect phase sequence or damage to the executive contactor’s contacts.

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