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

Overcurrent monitoring relay TRM-30F with display, 3-phase up to 25A

It serves to protect devices sensitive to operating current and voltage values from faults caused by:

• 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 overcurrent relay with display allows the current in each phase to be shown and protects 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 enabling current monitoring in each phase on the display. They can also check the cumulative voltage values between the phases.

With two output relays (1x NO, 1x NC), it is also possible to control or switch off the load when the overcurrent reaches a set value, or to activate a signaling 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 operation

1. Connect the device according to the wiring diagram. Incorrect connections can damage the device.
2. Set the device's overcurrent with the ">A" control according to the operating current of the load to be checked.
3. When the device is switched on, the set overcurrent value appears on the upper display within the first second and the error wait time on the middle display.
4. After one second, the actual current values of the phases are displayed and the display LED lights up.
5. When the "V/A/RESET" button is pressed, the values of the combined voltage between the phases are displayed.

Driver

• "A>" - setting of the allowable overload; the value is shown on the upper display.
• "Sec." - setting of the wait time for overcurrent error; the value is shown on the middle display.

Contact status

• NO 95-96, NC 97-98:

• Device unpowered or in error state: NO open, NC closed.
• Device powered and without error: NO open, NC open.

LED display

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

Function of the "V/A/RESET" button

• Reset: Pressing for 3 seconds clears the fault, LED "A" goes out, the closer switches on, the opener 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 the fault state: when the set overcurrent is exceeded, the set time is waited. Phase display blinks, LED "A" lights up, NO open, NC closed, LED NOR off.
• Leaving the fault state: current below setpoint, press reset for 3 seconds.

2. Protection against current asymmetry:

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

3. Overvoltage protection (U>440 V):

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

4. Undervoltage protection (U<265 V):

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

5. Protection against voltage asymmetry:

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

6. Phase sequence protection:

• If the phase connection is incorrect, the LED "XI" lights up.

Calculation of current asymmetry

The device calculates asymmetry according to the following formula:

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

Technical data

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