| Load Type |
Load
Characteristics |
Line Power Configuration |
Load
Configuration |
Phase- Angle Control |
Zero- Fire Control |
On/Off
Control |
Constant Resistance Elements:
-NICHROME
-KANTHAL
-CALROD
|
Resistance Nominally
Constant
<50% change versus temperature. |
Single-Phase |
Line-to-line or Line-to-neutral |
18D
18TB
18TBP |
18DZ
11DZ-P |
11D |
| Three-Phase |
Balanced or Delta Connected
loads, isolated from ground |
18E |
18EZ
11EZ-P |
11E |
| Grounded and/or Unbalanced loads |
18E-SW |
NA |
NA |
Variable Resistance Elements:
Quartz tubes,
T-3 Lamps,
some infrared
panels
|
High hot:cold
resistance ratio
causes high inrush currents when elements are cold.
|
Single-Phase |
Line-to-line or Line-to-neutral |
18D-H |
NA |
NA |
Three-Phase
|
Balanced or Delta Connected
loads, isolated from ground |
18E-H |
NA |
NA |
Balanced or Delta Connected
loads, isolated from ground |
18E-SW |
NA |
NA |
Silicon-Carbide Elements:
"GLO-BAR"
(direct coupled) |
Resistance
increases as
elements age. |
Single-Phase
|
Line-to-line or Line-to-neutral |
18D-H |
NA |
NA |
Three-Phase
|
Balanced or Delta Connected
loads, isolated from ground |
18E-H |
NA |
NA |
Balanced or Delta Connected
loads, isolated from ground |
18E-SW |
NA |
NA |
| Transformer-Coupled Loads:
(heating elements driven from the secondary winding of a
transformer)
|
Inductive Load
with initial current
inrush. |
Single-Phase
|
Line-to-line or Line-to-neutral |
18D-SW |
NA |
NA |
Three-Phase
|
Balanced
three-phase transformers |
18E-SW |
NA |
NA |
Scott-T connected/
unbalanced transformers |
18E-SW |
NA |
NA |
Inductive or Resistive DC Loads:
magnets, fields, electrolytic cells |
Resistive:
load resistance nominally constant. Inductive and
DC fields |
Single-Phase
|
DC Power required |
36D |
NA |
36D |
Three-Phase
|
DC Power required |
36E |
NA |
36E |
