TM-D thermal-magnetic trip units
TM-D, for protection of cables on distribution systems supplied by transformers
Protection
Thermal protection (Ir)
Thermal overload protection based on a bimetal strip providing an inverse time curve
I2 t, corresponding to a temperature rise limit. Above this limit, the deformation of the
strip trips the circuit breaker operating mechanism.
This protection operates according to:
- Ir that can be adjusted in amps from 0.7 to 1 times the rating of the trip unit (16 A to
250 A), corresponding to settings from 11 to 250 A for the range of trip units - a non-adjustable time delay, defined to ensure protection of the cables.
Magnetic protection (Im)
Short-circuit protection with a fixed or adjustable pick-up Im that initiates
instantaneous tripping if exceeded.
- ●TM-D: fixed pick-up, Im, for 16 to 160 A ratings and adjustable from 5 to 10 x In for
200 and 250 A ratings - ●fixed pick-up for 16 to 63 A ratings.
Protection against insulation faults
Two solutions are possible by adding:
- a Vigi add-on acting directly on the trip unit of the circuit breaker
- a Vigirex relay connected to an MN or MX voltage release.
MicroLogic 2 trip unit
Circuit breakers equipped with MicroLogic 2 trip units can be used to protect，distribution systems supplied by transformers. For generators and long cables, MicroLogic 2 G trip units offer better suited low pick-up solutions
Protection
Settings are made using the adjustment dials with fine adjustment possibilities
Overloads: Long time protection (Ir)
Inverse time protection against overloads with an adjustable current pick-up Ir set using a dial and a non-adjustable time delay tr.
Short-circuits: Short-time protection with fixed time delay (Isd)
“Protection with an adjustable pick-up Isd. Tripping takes place after a very short
delay used to allow selectivity with the downstream device.”
Short-circuits: Non-adjustable instantaneous protection
Instantaneous short-circuit protection with a fixed pick-up.
Indications
Front indications
·Green “Ready” LED: flashes slowly when the circuit breaker is ready to trip in the event of a fault.
·Orange overload pre-alarm LED: steady on when I > 90 % Ir.
·Red overload LED: steady on when I > 105 % Ir.
Remote indications
An overload trip signal can be remoted by installing an SDx relay module inside the circuit breaker.
This module receives the signal from the MicroLogic electronic trip unit via an optical link and makes it available on the terminal block. The signal is cleared when the circuit breaker is reclosed.
MicroLogic 1.3 M for magnetic protection only
MicroLogic 1.3 M trip units provide magnetic protection only, using electronic technology. They are dedicated to 400/630 A 3-poles (3P 3D) circuit breakers or 4-pole circuit breakers with detection on 3 poles (4P, 3D) and are used in certain applications to replace switch-disconnectors at the head of switchboards. They are especially used in 3-poles versions for motor protection
