1.6 Relay Coil and Contact Symbols
Commonly used symbols for relays of various kinds and applications are
illustrated in Figure 1.6 and 1.8 through 1.12. (ANSI Y32.2)
Fig. 1.6 Symbols for Relay Contact Combinations established by the American National Standards Institute (ANSI).
The heavy arrow indicates the direction of operation. Contact chatter may
cause some electrical discontinuity in forms D and E. Symbols taken from ANSI
C83.16-1971 and Y32.2-1975.
The proper polarization for a polarized relay is shown by the use of plus (+)
and (-) designations applied to the winding leads. The current in the
direction
indicated is to be interpreted to move, or tend to move, the armature toward
the contact shown nearest the coil on the diagram. If the relay is equipped
with numbered terminals proper numbers should be shown.
The following relay abbreviations are to be used on elementary wiring diagrams
drawn according to the Joint Industry Conference Standard for Industrial
Equipment (JIC):
| TYPE OF RELAY |
DESIGNATION |
| General use |
CR (1CR, 2CR, etc.) |
| Master |
CRM |
| Automatic |
CRA |
| Electronically Energized |
CRE(1CRE, 2CRE) |
| Manual (pushbutton) |
CRH |
| Latch |
CRL (1CRL, 2CRL) |
| Unlatch |
CRU (1CRU, 2CRU) |
| Time delay |
TR (1TR, 2TR) |
| Overload relay |
OL (1OL, 2OL) |
| Motor starter |
M (1M, 2M) |
Fig. 1.7 Preferred contact arrangement in a relay pileup.
Fig. 1.8 Symbol used in motor control relay circuits (JIC-NMTBA).
(a) Two wire control is generally thought of in relation to a pilot device such
as a thermostat, pressure switch, etc., or to a simple maintained SPDT toggle
or push-button switch. As the term implies, these devices require the use of
only two wires between the control unit and the starter. The device is
connected in series with the main contactor coil of the starter and the opening
or closing of the pilot device directly controls the de-energizing or energizing
of the starter. The major feature of a two wire control system is low voltage
release. The starter drops out in the event of a power failure but picks up or
recloses automatically when the power is restored, (b) In three wire control
the main contactor coil of the starter is wired in series with its own NO
auxiliary contacts. The "Start-Stop" push-button station, which requires the
use of three wires between the control and the starter, is connected in
parallel with the coil. In the event of a power failure, the starter will drop
out and remain de-energized until the "Start" button is depressed. Since the
starter drops out when there is a power failure and will not pick up or reclose
again until the start button is depressed, this Control system provides low
voltage protection.
Graphic Symbols is DoD mandatory. Section 22 covers letter designations for
components and "K" is the letter for relay-e.g., K1,K2,etc. See Footnote to
paragraph 1.1.
Fig. 1.9 Alternative symbols for relay contact combinations.
Sources of symbols: IEC-International Electrotechnical Commission; JIC-Joint
Industry Conference, Electrical Standards for Industrial Equipment;
NMTBA - National Machine Tool Builders Association/Electrical Standards.
Mod. Tel-Modern telephone practice. Note: CT indicates continuity transfer, one
asterisk denote Make-Before-Break, and two asterisks denote
Break-Make-Before-Break.
Fig. 1.10 Combined symbol of relay coil and its contacts.
APPLICATION: RELAY WITH TRANSFER CONTACTS
Fig. 1.11 Comparison Relay, Electronic and Logic symbols.
Fig. 1.12 Symbols used in cam-operated timer control.
