Wiring - Logic Inputs - TeSys T User Guides

Overview

10 logic inputs maximum are provided:

Six logic inputs on the LTMR controller, internally powered by the LTMR.
Four logic inputs on the LTME expansion module, independently powered.

Logic Inputs of the LTMR Controller

The controller LTMR has six logic inputs:

Available via field wiring terminals I.1- I.6.
Internally powered by the control voltage of the LTMR controller (the input voltage is the same voltage as the controller supply voltage.)
Isolated from the inputs of the LTME expansion module.

The three Common (C) terminals of the LTMR controller are connected to the A1 control voltage via an internal filter, as shown in the wiring diagram examples.

NOTICE
LOGIC INPUTS DESTRUCTION HAZARD Connect the LTMR controller’s inputs using the three Common (C) terminals connected to the A1 control voltage via an internal filter. Do not connect the Common (C) terminal to the A1 or A2 control voltage inputs. Failure to follow these instructions can result in equipment damage.

For more information, refer to the power supply wiring and the technical specifications of the LTMR controller in the TeSys T LTMR Motor Management Controller User Guide.

Logic Inputs of the LTME Expansion Module

The four logic inputs on the LTME expansion module (I.7 - I.10) are not powered by the control voltage of the LTMR controller.

For more information, refer to the technical specifications of the LTME expansion module in the TeSys T LTMR Motor Management Controller User Guide and to the power supply description.

Controller AC Inputs Setting

The LTMR controller uses digital filters to obtain a correct AC signal on the inputs.

For more accurate results, this filter can be configured by the controller AC inputs setting register to set the voltage supply and activate the adaptive filtering internal feature.

Connection of the Logic Inputs

NOTICE
UNINTENDED EQUIPMENT OPERATION Install interposing relay for long distance inputs. Segregate control cable from power cable. Use dry contact on LTMR inputs. Respect the recommendations given in this chapter. Failure to follow these instructions can result in unwanted motor stops.

Three types of connection are possible:

Direct connection for all information on logic inputs coming from the switchboard.
Connection via interposing relays for all information on logic inputs coming from outside of the switchboard and mainly connected with long lines.

Using interposing relays reduces EMC disturbance effects on the LTMR controller and improves the reliability of the information.
Connection without interposing relays for logic input on short distance.

For TeSys T inputs / outputs applications, only dry contacts free of potential can be used. Otherwise, current could be supplied to sensor or device and affect the input / output state.

Inductive Interference

For parallel cable runs above 100 m (328 ft) with close proximity between control and power, an induced voltage can be generated and cause the relay to remain blocked. It is highly recommended to separate control and power with 50 cm (1.64 ft) space or use separation plate. To limit the induced voltage in AC, it is possible to add a clamping resistor in parallel of the interposing relay.

Maximum Distance Without Interposing Relay

The maximum distance allowed without interposing relay is addressed below:

Wire Size	1 mm² (AWG 18)	1.5 mm² (AWG 16)	2 mm² (AWG 14)	2.5 mm² (AWG 14)
Maximum distance for wires	210 m (689 ft)	182 m (597 ft)	163 m (535 ft)	149 m (489 ft)

However, due to variability of installations it is highly recommended to use interposing relays for control cable lengths longer than 100 m (328 ft).

Recommended Interposing Relay

Interposing relays must have the following characteristics:

Electromechanical relay with 2.5 kVac isolation minimum.
Self-cleaning or low level contact (I < 5 mA).
Installed in the switchboard as close as possible to the LTMR controller.
AC or DC control circuit voltage, supplied by separate power supply (not supplied by the same power supply as the LTMR controller to respect the galvanic isolation).

In case of long distances between the process and the LTMR controller, interposing relays with DC control circuit voltage are recommended.

The protection module is mandatory on the interposing relays in order to suppress the surge.

The following Schneider Electric RSB1 interposing relays are recommended:

Reference Number	Control Circuit Voltage	Protection Module
RSB1A120•D	6, 12, 24, 48, 60, 110 Vdc	Diode RZM040W
RSB1A120•7	24, 48 Vac	RC circuit RZM041BN7
RSB1A120•7	120, 220, 230, 240 Vac	RC circuit RZM041FU7

Use of DC Interposing Relays

The DC interposing relays are recommended because long wires distances can be used to command the relay.

DC RSB1 relay voltage	24 Vdc	48 Vdc	110 Vdc
Maximum distance for wires in parallel without metallic screening	3,000 m (10,000 ft)	3,000 m (10,000 ft)	3,000 m (10,000 ft)
Maximum distance for wires in parallel with metallic screening	3,000 m (10,000 ft)	3,000 m (10,000 ft)	3,000 m (10,000 ft)

The following diagram shows an example when using DC interposing relays:

Use of AC Interposing Relays

The use of an AC interposing relay is allowed only on short distances if an AC voltage is mandatory.

AC RSB1 relay voltage	24 Vac	48 Vac	120 Vac	230/240 Vac
Maximum distance for wires in parallel without metallic screening	3,000 m (10,000 ft)	1,650 m (5,500 ft)	170 m (550 ft)	50 m (165 ft)
Maximum distance for wires in parallel with metallic screening	2,620 m (8,600 ft)	930 m (3,000 ft)	96 m (315 ft)	30 m (100 ft)

The following diagram shows an example when using AC interposing relays:

Use of AC Interposing Relays with a Rectifier

The use of AC interposing relay with a rectifier is recommended on long distances if an AC voltage is mandatory.

Add a rectifier composed of 1 A / 1,000 V diodes to command an AC interposing relay. In this way, rectified AC current flows in the control cable when the switch in the continuous part is closed.

Relay drop out time increases with the stray capacitance (long cable length) because the capacitance reduces the inductive behavior of the coil. The equivalent component tends to be a resistor increasing the drop-out time. Moreover, the more the voltage is high the more the phenomenon is important.

AC RSB1 relay voltage	24 Vac	48 Vac	120 Vac	230/240 Vac
Maximum distance for wires in parallel without metallic screening	3,000 m (10,000 ft)	3,000 m (10,000 ft)	3,000 m (10,000 ft)	3,000 m (10,000 ft)
Maximum distance for wires in parallel with metallic screening	3,000 m (10,000 ft)	3,000 m (10,000 ft)	3,000 m (10,000 ft)	3,000 m (10,000 ft)

The following diagram shows an example when using AC interposing relays with a rectifier: