Preface
This is the seventh edition of CSA Standard C22.2 No. 77, Motors with Inherent Overheating Protection, part of a series of Standards issued by the Canadian Standards Association under Part II of the Canadian Electrical Code. It supersedes the previous editions published in 1942, 1957, 1970, 1972, 1976, and 1988.
Major changes included in this edition are as follows:
(a) old Clauses 6.4.2 and 6.4.7 are deleted;
(b) one-shot protectors are now referred to by the more correct term, thermal cutoffs;
(C) numerous changes required to harmonize with UL Standards 51 9 and 547 are incorporated, including new Clauses 1.4, 4.3, 4.4, 5.1.8, and 5.9;
(d) Clause 4.1 .5 covering protectors connected in an external control circuit is new;
(e) test voltage is specified in Clause 5.2.1 and new Table 6, which replace old Clause 6.2.1;
(f) Clause 5.4.5 is rearranged for clarity. As well, Classes F and H are added to Clause 5.4.5.2, and Clause 5.4.5.3 is new;
(g) Clause 5.6.1 is revised adding pass/fail criteria and the recommendation that a visual indicator be employed to show if the 3 A fuse opens;
(h) Clause 6 is revised in several locations;
(i) the Note to Table 2 is revised to clarify the calculation of average temperature;
(j) single-operation protectors are included; and
(k) numerous other editorial improvements are incorporated.
For general information on the Standards of the Canadian Electrical Code, Part II, see the Preface of CSA Standard CAN/CSA-C22.2 No. 0, General Requirements—Canadian Electrical Code, Part II.
This Standard was prepared by a Subcommittee of the Technical Committee on Industrial Products under the jurisdiction of the Standards Steering Committee on Canadian Electrical Code, Part II, and was formally approved by these Committees.
Scope
1.1
This Standard applies to ac and dc motors with inherent overheating protection designed to be used in accordance with the Canadian Electrical Code, Part I, as follows:
(a) motors with a voltage rating not exceeding 600 V and with a protective device connected in the motor circuit;
(b) impedance-protected motors with a voltage rating not exceeding 600 V; and
(c) motors with a voltage rating not exceeding 5000 V and having a protective device connected in an external control circuit with a voltage rating not exceeding 600 V.
1.2
This Standard applies to motors with protective devices that are responsive to
(a) motor temperature alone; or
(b) motor temperature and motor current passing through the device, but does not apply to motors with protective devices that are responsive to current alone.
1.3
This Standard does not apply to sealed (hermetic) type motor compressors with inherent overheating protection (see CSA Standard C22.2 No. 140.2).
1.4
A product that contains features, characteristics, components, materials, or systems new or different from those in use when the Standard was developed, and that involves a risk of fire, electric shock, or injury to persons shall be evaluated using the appropriate additional component and end-product requirements as determined necessary to maintain the level of safety for the user of the product as originally anticipated by the intent of this Standard.
