Digital overcurrent relay with voltage protection and 3×3 digit LED display TRM-30F

TRM-30F overcurrent monitoring relay with display, three-phase up to 25A

It is designed to protect equipment sensitive to operating current and voltage values from errors that may occur due to:

• overcurrent overload (adjustable current value 0.5 ... 30 A)
• current asymmetry (50%, fixed value)
• voltage asymmetry (30%, fixed value)
• overvoltage and undervoltage (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 loss, and phase reversal. These digital overload relays are designed to prevent damage to the motor/load caused by high currents, while allowing monitoring of the current flowing in each phase on the display. They can also monitor cumulative voltage values between phases.

Thanks to the two output relays (1x NO, 1x NC), it is also possible to control or disconnect the load when an overcurrent setpoint is reached, or activate a signaling contact to the control system. The TRM-xx digital relays are equipped with built-in current transformers and a 3x3 digit display for current visualization.

Application and operating principle

1. Connect the device according to the wiring diagram. Incorrect connections can damage the device.
2. Set the device overcurrent using the command ">A" based on the operating current of the load to be controlled.
3. When the power supply is connected, the set overcurrent value appears on the upper display and the error waiting time on the central display within the first second.
4. The actual values of the phase currents will be displayed after one second of operation and the indicator LED will light up.
5. Pressing the "V/A/RESET" button displays the combined voltage values between the phases.

Drives

• "A>" - setting of the allowed overload; the value is displayed on the upper display.
• "sec." - setting of the overcurrent fault delay time; the value is displayed on the central display.

Contact status

• NO 95-96, NC 97-98:

• Device de-energized or in fault condition: NO open, NC closed.
• Device energized and fault-free: NO open, NC open.

LED indication

• "V" LED - lights up in case of overvoltage/undervoltage or voltage asymmetry error.
• "A" LED - lights up in case of high current or current asymmetry error.
• "XI" LED - lights up when the phase sequence is incorrect.
• "NOR" LED - lights up when the device is powered and the system is error-free.

Function of the "V/A/RESET" button

• Reset: Pressing for 3 seconds clears the fault, the "A" LED turns off, the NO contact turns on, the NC contact opens.
• V/A: a short press switches the display between current and voltage values.

Protection and operating principle

1. Overcurrent protection (0.5-30 A):

• Entering fault state: when the set overcurrent is exceeded, wait the set time. The phase display flashes, the "A" LED is on, NO open, NC closed, NOR LED off.
• Exit error condition: current below setpoint, press the reset button for 3 seconds.

2. Current asymmetry protection:

• Input: current difference between phases >50%, wait 3 seconds, the display flashes, the "A" LED is on.
• Output: difference <50%, press reset for 3 seconds.

3. Overvoltage protection (U>440 V):

• Input: voltage >440 V, wait 3 seconds, the display flashes, the "V" LED lights up.
• Output: voltage <435 V for 3 seconds.

4. Undervoltage protection (U<265 V):

• Input: voltage <265 V, wait 3 seconds, the display flashes, the "V" LED lights up.
• Output: voltage >270 V for 3 seconds.

5. Voltage asymmetry protection:

• Input: voltage difference >30%, wait 3 seconds, the display flashes, the "V" LED lights up.
• Output: difference <30% for 3 seconds.

6. Phase sequence protection:

• An incorrect phase connection lights up the "XI" LED.

Calculation of current asymmetry

The instrument calculates asymmetry according to the formula:

Example: ((25 - 15) / 25) × 100 = 40% current asymmetry.

Technical specifications

• Supply voltage: measured voltage 3f 3x400 VAC
• Operating voltage (Un): 3x380 VAC 50/60 Hz, self-consumption <10 VA
• Adjustable overcurrent (Overload): 0.5-30 A
• Fault waiting time (t): 0-20 s
• Display: 3x3 digits, 9 mm height, 7 indication LEDs
• Overvoltage: 440 V (L-L)
• Undervoltage: 265 V (L-L)
• Voltage asymmetry: 30%
• Current asymmetry: 50%
• Asymmetry error waiting time: 3 s
• 2x output relays (1x NO, 1x NC): 3 A / 250 V AC (resistive load)
• Connection type: screw terminals
• Cable section: 2.5 mm² (relay contacts) / 6 mm² (input and output loads for measurement)
• Weight: max. 380 g
• Mounting: on DIN rail
• Operating temperature: -20°C ... +55°C
• Operating altitude: <2000 m