Technical Support - Control Equipment

STANDARD TERMINAL MARKINGS

The Terminal markings of the Citation M Contactor and Relay range are in accordance with the European standard EN50005. This European standard has been given the status of British Standard 5472 from 1st May, 1977.

The standard EN covers the requirement of providing terminal markings to coils, main contacts and auxiliary contacts in order to identify the incoming and outgoing terminals in each case and the mode of contact between those terminals.

Coils
The markings of the terminals of coils are alphanumeric. Capital alphas are preferred and incoming terminals are identified by odd numbers and the corresponding outgoing terminal identified by the next higher number.

Contacts
The markings of terminals of contacts of switching devices with two positions are identified to indicate whether they are main contacts or auxiliary contacts.

Main contacts
The terminals of main contacts are identified by single figure numbers. Each terminal marked by an odd number is associated with the terminal marked by the following even number. The odd number indicates the incoming terminal and the even number indicates the outgoing terminal.

Auxiliary contacts
Terminals of auxiliary contacts are identified by two figure numbers. The first figure is a sequence number to indicate the number of auxiliary contacts on the device, the selection of the sequence number is purely sequential. The second figure is a function figure. Function numbers 1 and 2 are allocated to break contacts and function numbers 3 & 4 to make contacts.

Changeover contacts
The terminals of changeover contacts are marked by the function numbers 1,2 and 4. In this illustration the sequence number is represented by the anonymous.

PROTECTION

Degrees of protection needed by housing.

The following indices or symbols are given for each unit:

Protection index - in accordance with standard NFC 20010. This index comprises the letters IP or IPW (protection against inclement weather conditions) followed by three digits (see table below).

Degree of protection for persons against electric shock – particularly important where electrical equipment is used in bathrooms and washrooms . (standard C15100).

Standard NF-C 20030 defines four classes of equipment.
Class 0 - equipment with functional insulation, without ground connection.
Class 1 - equipment with functional insulation, with ground connection.
Class 2 - equipment with double insulation, or reinforced insulation, without ground connection.
Class 3 - equipment of operation at very low voltage only.

Protection symbols as follows:

Click here to view figures

Control gear
An efficient means of switching off has to be provided for every fixed electric motor, the means of switching off has to be readily accessible, easily operated and so placed as to prevent danger.
130-06-02

Control equipment which requires operation or attention by a person shall be installed so that adequate and safe access and working space is available for such operation or attention.
130-07-01

Where electrical equipment is to be exposed to the weather, corrosive conditions or other adverse conditions, it shall be so constructed or protected to prevent danger from such conditions.
130-08-01

Where equipment is installed in surroundings susceptible to the risk of fire or explosion, additional precautions, including the way the equipment is constructed,shall be taken to prevent danger.
130-08-02

Every circuit shall be provided with a means of isolation. In an installation forming part of a TN-S or TN-C-S system all phase conductors shall be isolated. In an installation forming part of an IT or TT system all live conductors shall be isolated.
461-01-01

Precautions shall be taken to prevent any equipment being inadvertently or unintentionally energised.
461-04-01

Every machine driven by electricity that may rise to danger shall be provided with a means of emergency stopping. The means of emergency stopping the machine shall be readily accessible and easily operated. Where more than one method is provided for starting the machine and the unexpected starting of the machine could cause danger;precautions shall be taken to prevent the machine restarting.
476-03-02

Any emergency switching device used shall be of the latching type or capable of being restrained in the off position. The release of the emergency switching device shall not re-energise the equipment it controls.
537-04-05

Where motors are subject to frequent starting and stopping,the effect of the temperature rise on the equipment and conductors caused by the frequent starting and stopping, shall be taken into account.
552-01-01

Motors having a rating exceeding 0.37kW shall be provided with overloads.
552-01-02

Unless a danger could arise if a motor did not restart after a brief interruption of the supply, every motor shall be provided with a no-volt release where the unexpected restarting of the motor might cause danger.
522-01-03

Co-ordination is required between overload devices and fault current protection devices, such that the energy let-through the fault current device is within the withstand capacity of the overload device.
435-01-01

For compliance with 413-02-04 and for a voltage to earth UO of 220V to 277V the earth loop impedance shall not exceed ZS =Uo where UO is the nominal voltage to earth and la is the current required la to disconnect the protective device in 5 seconds.
413-02-08

Where a final circuit only supplies stationary equipment a disconnection time of 5 seconds is permitted.
413-02-13

Where fixed equipment is outside the equipotential zone, and that equipment can be touched by a person in direct contact with earth,and the supply is obtained from within the equipotential zone, and the voltage to earth is in the range of 220V to 277V, then fixed equipment must be disconnected within 0.4 seconds when an earth fault occurs.
471-08-03

Where the voltage to earth is 240V r.m.s the disconnection time of 5 seconds can be achieved if the earth fault loop impedance ZS does not exceed the values given in table 41D for fuses and 41B2 for mcbs, or the Tables ZS 1 to 7 in the Handbook on the IEE wiring Regulations. Where the voltage to earth is 55V the value of earth loop impedance is given in Table ZS 8 in the handbook.
413-02-14

Where the voltage to earth is 240V r.m.s, the disconnection time of 0.4 seconds can be achieved if the earth fault loop impedance ZS does not exceed the values given in Table 4B1 for fuses or 41B2 for mcbs or the Tables ZS 1 to 7 in the Handbook on the IEE wiring Regulations.
413-02-10

USEFUL FORMULAE

Click here to view Table 1
Click here to view Table 2