Power Control
Application Guide
| 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 |
PS |
ZS
|
NA |
| Three-Phase |
Balanced or Delta Connected
loads, isolated from ground |
PT |
ZT |
NA |
| Grounded and/or Unbalanced loads |
PTX |
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 |
PSH |
NA |
NA |
Three-Phase
|
Balanced or Delta Connected
loads, isolated from ground |
PTH |
NA |
NA |
Balanced or Delta Connected
loads, isolated from ground |
PTX |
NA |
NA |
Silicon-Carbide Elements:
"GLO-BAR"
(direct coupled) |
Resistance
increases as
elements age. |
Single-Phase
|
Line-to-line or Line-to-neutral |
PSH |
NA |
NA |
Three-Phase
|
Balanced or Delta Connected
loads, isolated from ground |
PTH |
NA |
NA |
Balanced or Delta Connected
loads, isolated from ground |
PTX |
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 |
PSX |
NA |
NA |
Three-Phase
|
Balanced
three-phase transformers |
PTX |
NA |
NA |
Scott-T connected/
unbalanced transformers |
PTX |
NA |
