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Overcurrent relay TRM-30F with display, 3-phase up to 25A
It is designed to protect equipment sensitive to operating current and voltage values from faults that may occur due to:
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current overload (adjustable current value 0.5 ... 30 A)
- current asymmetry (50%, fixed value)
- voltage asymmetry (30%, fixed value)
- over and under-performance (Umin: 265 V, Umax: 440 V, fixed value).
The TRM-30F digital overcurrent relay with display allows you to view the current in each phase and protect the motor or device from overcurrent, overvoltage, undervoltage, phase failure and phase reversal. These digital overload relays are designed to prevent motor/load damage from excessive current, while allowing current monitoring in each phase on the display. They are also able to check the cumulative voltage values between phases.
Thanks to two output relays (1x NO, 1x NC), it is also possible to control or interrupt the load when the overcurrent setpoint is reached, or to switch on an alarm contact for the control system. TRM-xx digital relays have built-in current transformers and a 3x3-digit display for current indication.
Application and operating principle
- Connect the device according to the wiring diagram. Incorrect connections can damage the device.
- Set the overcurrent of the device using the ">A" adjustment according to the operating current of the controlled load.
- When the device is connected, the set overcurrent value appears on the upper display and the fault waiting time appears on the middle display for the first second.
- The actual values of the phase currents are displayed after one second and the indicator LED lights up.
- When the "V/A/RESET" button is pressed, the combined voltage values between the phases are displayed.
Control elements
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"A> " - setting the permissible overload; the value is displayed on the upper indicator.
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"sec." - setting the overcurrent fault waiting time; the value is displayed on the middle indicator.
Contact status
- Device unpowered or in fault condition: NO open, NC closed.
- Device powered and without fault: NO open, NC open.
Indicator LED
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LED "V" - lights up in case of over/undercurrent or voltage asymmetry fault.
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LED "A" - lights up in case of high current or current asymmetry fault.
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LED "XI" - lights up if the phase sequence is incorrect.
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LED "NOR" - lights up when the device is energized and the system is fault-free.
Function of the "V/A/RESET" button
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Reset: A 3-second press clears the fault, LED "A" turns off, NO contact switches on, NC contact opens.
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V/A: A short press toggles the display between current and voltage values.
Protection and operating principle
1. Overcurrent protection (0.5-30 A):
- Entering fault condition: if the set overcurrent is exceeded, the set time is waited. The phase indicator flashes, LED "A" lights up, NO open, NC closed, LED NOR off.
- Exiting fault condition: current below set value, press reset for 3 seconds.
2. Protection against current asymmetry:
- Input: current difference between phases >50%, wait 3 seconds, display flashes, LED "A" lights up.
- Exit: difference <50%, press reset for 3 seconds.
3. Overvoltage protection (U>440 V):
- Input: voltage >440 V, wait 3 seconds, display flashes, LED "V" lights up.
- Exit: voltage <435 V for 3 seconds.
4. Undervoltage protection (U<265 V):
- Input: voltage <265 V, waits 3 seconds, display flashes, LED "V" lights up.
- Exit: voltage >270 V for 3 seconds.
5. Protection against voltage asymmetry:
- Input: voltage difference >30%, waits for 3 seconds, display flashes, LED "V" lights up.
- Departure: difference <30% for 3 seconds.
6. Phase sequence protection:
- Incorrect phase connection lights up LED "XI".
Current asymmetry calculation
The device calculates asymmetry according to the formula:
Example: ((25 - 15) / 25) × 100 = 40% current asymmetry.
Technical data
- Supply voltage: measured voltage 3ph 3x400 VAC
- Operating voltage (Un): 3x380 VAC 50/60 Hz, self-power <10 VA
- Adjustable overcurrent (overload): 0.5-30 A
- Fault delay time (t): 0-20 s
- Display: 3x3 digits, 9 mm height, 7 indicator LEDs
- Overvoltage: 440 V (L-L)
- Undervoltage: 265 V (L-L)
- Voltage asymmetry: 30%
- Current asymmetry: 50%
- Asymmetry error delay time: 3 s
- 2x output relays (1x NO, 1x NC): 3 A / 250 V AC (resistive load)
- Connection type: screw terminals
- Cable cross-section: 2.5 mm² (relay contacts) / 6 mm² (input and output loads for measurement)
- Weight: max. 380 g
- Installation: DIN rail
- Operating temperature: -20°C ... +55°C
- Operating altitude: <2000 m
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