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

TRM-30F overcurrent control relay with display, 3-phase up to 25A

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

• current 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 overload relay with display allows you to see 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 damage to the motor/load from high currents while allowing the display to monitor the current flowing in each phase. They can also check cumulative voltage values between phases.

With two output relays (1x NO, 1x NC), it is also possible to control or disconnect the load when the overcurrent reaches the set value, or to activate a signal contact to the control system. The TRM-xx digital relays have built-in current transformers and a 3x3-digit display for current indication.

Application and operating principle

1. Connect the device according to the wiring diagram. Incorrect connection may cause device damage.
2. Set the device's overcurrent using the ">A" control according to the operating current of the load you will be monitoring.
3. When power is connected, within the first second the set overcurrent value will appear on the upper display, and the fault delay time on the middle display.
4. The actual phase current values will be shown after one second of operation, and the indicator LED will light up.
5. When the "V/A/RESET" button is pressed, the combined voltage values between phases are displayed.

Drivers

• "A>" - setting the allowable overload; the value is shown on the upper display.
• "sec." (second) - for power interruption. - setting the delay time for overcurrent fault; the value is shown on the middle display.

Contact status

• NO 95-96, NC 97-98:

• The device is disconnected from power or in a fault state: NO open, NC closed.
• The device is powered and fault-free: NO open, NC open.

Indicator LED

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

"V/A/RESET" button function

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

Protection and operation principle

1. Overcurrent protection (0.5-30 A):

• Enter fault state: when the set overcurrent is exceeded, the set time is waited. Phase display flashes, "A" LED lights up, NO open, NC closed, "NOR" LED off.
• Exit fault state: current is below the set value, press reset for 3 seconds.

2. Current asymmetry protection:

• Entry: current difference between phases >50%, wait 3 seconds, display flashes, "A" LED lights up.
• Exit: difference <50%, press reset for 3 seconds.

3. Overvoltage protection (U>440 V):

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

4. Undervoltage protection (U<265 V):

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

5. Voltage asymmetry protection:

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

6. Phase sequence protection:

• If the phases are connected incorrectly, the "XI" LED lights up.

Calculating current asymmetry

The device calculates current asymmetry according to the formula:

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

Technical specification

• Supply voltage: measured voltage 3f 3x400 VAC
• Operating voltage (Un): 3x380 VAC 50/60 Hz, own power <10 VA
• Adjustable overcurrent (overload): 0.5-30 A
• Fault delay time (t): 0-20 s
• Display: 3x3 digits, 9 mm height, 7 LEDs for indication
• Overvoltage: 440 V (L-L)
• Undervoltage: 265 V (L-L)
• Voltage asymmetry: 30%
• Current asymmetry: 50%
• Asymmetry fault 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 measurement loads)
• Weight: max. 380 g
• Mounting: on DIN rail
• Operating temperature: -20°C ... +55°C
• Operating altitude: <2000 m