ABB Selecting switches Application Information

Selecting switches

per CEC & IEC

Selecting switches per CEC

Section 28 of the Canadian Electric Code includes two methods for properly sizing disconnect switches:

1. Single motor application

A properly sized disconnect switch for a single motor will:

a) have an ampere rating greater than or equal to 115 percent

of the rated motor full load current; or,

b) have a HP rating greater than or equal to the rated motor HP

(at applied voltage) if the disconnect switch under
consideration is HP rated.

2. Combination load application

A properly sized disconnect switch for a combination load will
be selected by adding all the simultaneous individual loads in
the circuit under consideration.

Using motor nameplate information, load information, and
tables from section 28 of the CEC, determine one equivalent
full load current and plus 15% of the largest motor determine
an equivalent HP rating. Select a disconnect switch:

a) greater than or equal to 115 percent of the equivalent full

load current; and,

b) greater than or equal to the equivalent HP rating.

Selecting switches per IEC

Utilization categories

Nature of current Utilization category Typical applications

Frequent operation Infrequent operation

AC-20A AC-20B • Connecting and disconnecting under no-load conditions

AC-21A AC-21B • Switching of resistive loads including moderate overloads
(PF > 0.95)

Alternating current AC-22A AC-22B • Switching of mixed resistive and inductive loads, including

moderate overloads (PF > 0.65)

AC-23A AC-23B • Switching of motor loads or other highly inductive loads
(PF > 0.45 below 100A; PF > 0.35 above 100A)

DC-20A DC-20B • Connecting and disconnecting under no-load conditions

DC-21A DC-21B • Switching of resistive loads including moderate overloads
(L/R < 1ms)

Direct current DC-22A DC-22B • Switching of mixed resistive and inductive loads, including

moderate overloads e.g., shunt motors (L/R < 2.5ms)

DC-23A DC-23B • Switching of highly inductive loads e.g., series motors
(L/R < 15ms)

Mechanical endurance Number of operations Number of operations

100A 10,000 2000

315A 8000 1600

>315A 2000 400

•Category AC-23 includes occasional switching of individual motors. The switching of capacitors of tungsten filament lamps shall be subject to agreement between
manufacturer and user.

General information : 1.1 – 1.7 Complete Non-fusible switches: 1.8 – 1.9 Components: 1.10 – 1.23 Technical information: 1.24– 1.29 Dimensions: 1.30 – 1.42

Discount schedule DS-H

1.31

Use of CSA C22.2 No. 4 & No. 14 Disconnects

According to CEC

®

Section 28

Motor Feed

Motor feeder short circuit and ground

fault protection

Motor disconnecting means

(CEC ® 28-600, 28-604 (1)

600 (1), 28-602 (1)

Motor branch-circuit

short-circuit

protection

(CEC ® 28-200…28-210)

Motor controller

(CEC ® 28-500…28-504)

CSA C22.2 No. 4

Non-fusible Switches

OT30, OT60, OT100,
OT160, OT200, OT400,
OT600, OT800, OT1200,
OETL-NF1600...NF2000

CSA C22.2 No. 4

Fusible Switches

OS30, OS60, OS100,
OS200, OS400,
OS600, OS800, OS1200

Typical control panel

Motor overload protection

(CEC ® 28-302…28-308

OSHA Lockout/tagout disconnect

(CEC ® 28-600(3), 28-602(2), 28-604(2)

CSA C22.2 No. 14

Non-fusible Switches

OT16, OT25, OT40,
OT63, OT80
(CSA C22.2 No.4 switches
can also be applied)

Motor

General information : 1.1 – 1.7 Complete Non-fusible switches: 1.8 – 1.9 Components: 1.10 – 1.23 Technical information: 1.24– 1.29 Dimensions: 1.30 – 1.42

Discount schedule DS-H

1.32