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

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

It is intended to protect the equipment sensitive to operational current and voltage values before errors that may can 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)

Digital overcurrent overload relay TRM-30F with the display allows showing the current in each phase and protecting the motor or the appliance from overcurrent, overvoltage, undervoltage, phase loss, and change of order of phases. These digital overload relays are designed to prevent damage to the motor/load from high currents and simultaneously allow for monitoring the current flowing in each phase on the display. They can also monitor the values of the combined voltage between phases.

With two output relays (1x NO, 1x NC), it is it is also possible to control or disconnect the load when the set overcurrent value is reached, or turn on the signaling contact to the control system. Digital relay TRM-xx have built-in current transformers and a 3x3-digit display for showing current.

Usage and principle of operation

1. Connect the device according to the connection diagram. Incorrect connection may damage the device.
2. Set the device's overcurrent using the controller ">A" according to the operating current of the load you will check.
3. After connecting the power supply during the first seconds on the top display will show the set value of overcurrent and on middle display error wait time.
4. The current values of currents from the phases will be displayed after one second of operation, and the indicator LED will light up.
5. After pressing the button "V/A/RESET" the values of the combined voltage between phases will be displayed.

Drivers

• "A>" – the allowed overload setting; value is displayed on the top display.
• "sec." – the error wait time setting overcurrent; the value is displayed on the middle display.

Contact status

• NO 95-96, NC 97-98:

• Device without voltage or in error state: NO open, NC closed.
• Device under voltage and without errors: NO closed, NC open.

Indicator LED

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

Button function "V/A/RESET"

• Reset: press for 3 seconds clears the error, LED “A” goes out, NO contact closes, NC contact opens.
• V/A: short press switches display between current and voltage values.

Protections and operating principle

1. Overcurrent protection (0.5–30 A):

• Entering error state: at exceeding the set overcurrent waits the set time. Phase display blinks, LED “A” is on, NO is open, NC is closed, LED NOR goes out.
• Release of error state: current below the set value, press reset for 3 seconds.

2. Protection against current asymmetry:

• Input: current difference between phases >50 %, waits 3 seconds, display blinks, LED “A” is on.
• Release: difference <50 %, press reset in 3 seconds.

3. Over-voltage protection (U>440 V):

• Input: voltage >440 V, waiting 3 seconds, the display flashes, LED “V” is lit.
• Departure: voltage <435 V for for 3 seconds.

4. Under-voltage protection (U<265 V):

• Input: voltage <265 V, waiting 3 seconds, the display flashes, LED “V” is lit.
• Departure: voltage >270 V for for 3 seconds.

5. Voltage asymmetry protection:

• Input: voltage difference >30 %, waiting 3 seconds, the display flashes, LED “V” is lit.
• Departure: difference <30 % for 3 seconds.

6. Phase sequence protection:

• Incorrect phase connection will light up the LED “XI”.

Calculation of current asymmetry

The device calculates the 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 V AC 50/60 Hz, own consumption <10 VA
• Adjustable overload: 0.5–30 A
• Waiting for error (t): 0–20 s
• Display: 3x3 digits, height 9 mm, 7 indicator LEDs
• Overvoltage: 440 V (L-L)
• Undervoltage: 265 V (L-L)
• Voltage asymmetry: 30 %
• Current asymmetry: 50 %
• Waiting for asymmetry error: 3 s
• 2x output relay (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 load for measurement)
• Weight: max. 380 g
• Mounting: on DIN rail
• Operating temperature: -20°C … +55°C
• Operating altitude: <2000 m