overloadrelay

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Thermal Overload Relay

101



PRINCIPLE OF OPERATION

The heating elements in the main circuit heat the bimetal tripping elements

corresponding to the motor load current. The heating elements are calibrated

such that the set trip point is achieved in accordance with the standards. By means

of trip bar, the movement / deflection of the bimetal is transmitted to plunger

which in turns operates the trip mechanism and thus the contacts are separated.

The trip point can be easily set on a scale in accordance with the nominal motor

rated current.

Bimetal elements for compensating the trip point in case of different ambient

temperature is fitted on the trip lever. Buttons are used for testing the circuit to

be protected, for resetting by hand and for conversion from manual to auto reset

mode.

DIFFERENTIAL MECHANISM

The relay operates on the differential system of protection provided by the double

slide mechanism. Under single phasing and unbalanced voltage conditions, the two

slides of the relay undergo differential def lection. One slide senses the movement

of the bimetal that has deflected the maximum, while the other senses the minimum

deflection.

The slides are linked in such a way that the difference in movements of the two

slides is amplified for actuation of the trip lever. This leads to accelerated tripping

under single phasing.

CONSTRUCTION

INTERNAL VIEW




Current RangeDirect Version 0.16A – 80A

CT Version 24A – 400A

Operational Voltage 550V

Insulation Voltage 750V

Ambient Temp. Range -25 o C to +55 o C

Mechanical Life (Ops) 0.1 million

Switching Frequency 15 Ops/ hr.

Operational Altitude 2000 mts.

Terminal Capacity

Main Terminals (Cable) 2 x 16 sq.mmAuxiliary Terminal (Cable) 2 x 4 sq.mm

Auxiliary CircuitInsulation Voltage 750V

Thermal Rating 10A

Contact Rating (AC 15 / DC 15)220 AC 2A

380/415V AC 1.5 A

220V DC 1 A

Type (kgs)

TRM 23 0.143

TRM 24 0.150

TRM 22 0.164

TRM 75 0.350

CTR 36 1.140

CTR 51 1.180

CTR 40 1.160

Type (kgs)

CTR 75 1.300

CTR 105 1.500

CTR 150 1.550

CTR 200 2.140

CTR 270 2.200

CTR 400 3.240

CTR 60 1.220

Weight

Terminal Markings

TECHNICAL INFORMATION

3 Phase Starting from cold condition

TRM 23 / 24 TRM 22 / 75

TIME CURRENT CHARACTERISTICS




DOL STARTING

3φφφφφ Motor Rating Approx. Full Overload Relay/CTR Backupat 415V 50Hz. Load Current Range fuse rating

HP KW Amp. Amp. Amp.

0.75 0.52 1.6 1.0-1.6 41 0.75 2.0 1.7-2.5 62 1.5 3.5 3.0-4.5 103 2.2 5.0 4.5-7.0 165 3.7 7.5 6.5-10 207.5 5.5 11.0 10-15 2510 7.5 14.0 13-19.5 2515.0 11.0 21.0 15-22 5020.0 15.0 28.0 24-34 5025.0 18.5 35.0 26-40 6330.0 22.0 40.0 34-51 8040.0 30.0 55.0 40-60 10050.0 37.0 66.0 50-75 12560.0 45.0 80.0 70-105 12575.0 55.0 100.0 100-150 16085.0 63.0 112.0 100-150 160100.0 75.0 135.0 100-150 200

STAR DELTA STARTING

3φφφφφ Motor Rating Full Load Full Load Overload Relay/CTR Backupat 415V 50Hz, line current phase current Range Fuse Rating

HP KW Amp. Amp. Amp. Amp.7.5 5.5 11.0 6.35 4.5-7.0 1610.0 7.5 14.0 8.08 6.5-10 2012.5 9.3 18.0 10.39 10-15 2515.0 11.0 21.0 12.12 10-15 2520.0 15.0 28.0 16.1 13-19.5 3225.0 18.5 35.0 20.2 15-22 5030.0 22.5 40.0 23.0 16-25 5035.0 26.0 47.0 26.90 24-34 63

50.0 37.0 66.0 38.1 26-40 8060.0 45.0 80.0 46.2 34-51 10075.0 55.0 100.0 57.7 40-60 10090.0 67.5 120.0 69.2 50-75 160100.0 75.0 135.0 77.9 70-105 160125.0 90.0 165.0 95.3 70-105 160150.0 110.0 200.0 115.5 100-150 200

RELAY SELECTION CHART




TRM 75

TRM 24TRM 23

TRM 22

DIMENSIONS (IN MM)




TYPE CTR 36 CTR 40 CTR 51 CTR 60 CTR 75 CTR 105 CTR 150 CTR 200/270/400*

A 127 127 157 157 157 183 185 - -

B 42 42 43 43 43 49 50 - -

C 59 59 59 59 59 59 59 - -

D 139 139 139 139 139 139 139 - -

TERMINAL BLOCK (TB 34) RELAY WITH TERMINAL BLOCK (TB 34)

CTR

* Dimensions on request.

DIMENSIONS (IN MM)


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