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

TRM-30F overload overvoltage relay with display, three-phase up to 25 A

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

• overcurrents (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 viewing the current magnitude in each phase and protecting the motor or device against overcurrent, overvoltage, undervoltage, phase failure and phase sequence change. These digital overload relays are designed to prevent motor/load damage caused by high currents, while allowing monitoring of the current flowing in each phase on the display. They are also able to check the 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 overload reaches the set value, or to activate an alarm contact for the control system. 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 connection diagram. Incorrect connections may damage the device.
2. Set the overcurrent of the device using the ">A" regulator according to the operating current of the load being tested.
3. When power is applied, the set overcurrent value will be displayed on the top display and the fault waiting time on the middle display during the first second.
4. The actual phase current values will be displayed after one second of operation and the indication LED will light up.
5. Pressing the "V/A/RESET" button displays the combined voltage values between phases.

Drivers

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

Contact status

• NO. 95-96, NC 97-98:

• Device without voltage or in fault condition: NO open, NC closed.
• Device under voltage and no fault: NO open, NC open.

Indication LEDs

• LED "V" - lights up in case of overvoltage/undervoltage or voltage asymmetry fault.
• LED "A" - lights up in case of high current or current asymmetry fault.
• LED "XI" - lights up if the phase sequence is incorrect.
• LED "NOR" - lights up if the device is under voltage and there are no faults in the system.

"V/A/RESET" button function

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

Protection and operating principle

1. Overload protection (0.5-30 A):

• Entering fault condition: when the set overcurrent is exceeded, the set time is waited. The phase display flashes, LED "A" is on, NO is open, NC is closed, LED NOR is off.
• Exiting fault condition: current is less than the set value, press reset for 3 seconds.

2. Current asymmetry protection:

• Entry: current difference between phases >50%, wait 3 seconds, display flashes, 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 flashes, LED "V" lights up.
• Exit: voltage <435 V, 3 seconds.

4. Undervoltage protection (U<265 V):

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

5. Voltage asymmetry protection:

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

6. Phase sequence protection:

• Incorrect phase connection lights up LED "XI".

Current asymmetry calculation

The device calculates 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, self-power <10 VA
• Adjustable overload current (overload): 0.5-30 A
• Fault wait 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 fault wait time: 3 s
• 2x output relays (1x NO, 1x NC): 3 A / 250 VAC (resistive load)
• Connection type: screw terminals
• Cable cross-section: 2.5 mm² (relay contacts) / 6 mm² (input and output for load measurements)
• Weight: max. 380 g
• Installation: on DIN rail
• Operating temperature: -20°C ... +55°C
• Operating altitude: <2000 m