Digital overload relay with voltage protection and LED display 3×3 digits TRM-30F

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

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

• current overload (adjustable current value from 0.5 to 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 visualization of the current in each phase and protects the motor or device against overcurrents, overvoltages, undervoltages, phase failures, and phase reversals. These digital overload relays are designed to prevent damage to the motor/load in case of high currents while allowing monitoring of the current flowing in each phase on the screen. They are also capable of checking the cumulative voltage values between phases.

With 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 to 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 indication.

Application and operating principle

1. Connect the device according to the wiring diagram. Incorrect connections may damage the device.
2. Set the device's overcurrent using the command ">A" based on the operating current of the load to be controlled.
3. When the device is powered on, the set overcurrent value is displayed on the upper screen and the error wait time on the central screen in 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. When the "V/A/RESET" button is pressed, the values of the combined voltage between the phases are displayed.

Conductors

• "A>" - setting of the permissible overload; the value is displayed on the upper screen.
• "sec. - setting of the overcurrent fault wait time; the value is displayed on the middle screen.

State of the contacts

• NO 95-96, NC 97-98 :

• Device powered off or in fault: NO open, NC closed.
• Device powered and without fault: NO open, NC open.

Indication LED

• LED "V" - turns on in case of overvoltage/undervoltage or voltage asymmetry error.
• LED "A" - turns on in case of high current or current asymmetry error.
• LED "XI" - turns on when the phase sequence is incorrect.
• LED "NOR" - turns on when the device is powered and the system has no errors.

Function of the button "V/A/RESET"

• Reset : a pressure of 3 seconds clears the fault, the LED "A" turns off, the NO contact turns on, the NC contact opens.
• V/A : a brief press allows switching from current value display to voltage value display.

Protection and operating principle

1. protection against overcurrents (0.5-30 A):

• Fault state input: when the set overcurrent is exceeded, the set time is waited. The phase display blinks, the LED "A" is on, NO open, NC closed, the NOR LED is off.
• Error state output: current below setpoint, press reset for 3 seconds.

2. Protection against current asymmetry:

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

3. Protection against overvoltage (U>440 V):

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

4. Protection against undervoltage (U<265 V):

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

5. Protection against voltage asymmetry:

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

6. Phase order protection:

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

Calculation of current asymmetry

The instrument calculates the asymmetry according to the following formula:

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

Technical characteristics

• 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
• Waiting time in case of a fault (t): 0-20 s
• Display: 3x3 digits, 9 mm height, 7 indication LEDs
• Overvoltage: 440 V (L-L)
• Undervoltage: 265 V (G-D)
• Voltage asymmetry: 30
• Current asymmetry: 50
• Waiting time for an 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