Extech Instruments 48VTR User Manual page 9

Control Output Relay Wiring
The control relay is accessed via terminals 8, 9, and 10. Terminals 8 and 9 constitute a
normally closed switch; terminals 8 and 10 constitute a normally closed switch. When
the controller activates the relay, the normally open and normally closed switches
change state. The relay itself does NOT provide its own power. AC power is wired as
shown in the wiring example below.
Control Device
External
Power
i.e., Heater, Valve,
Source Pump, Switch, etc.
8 9
Normally Open (N.O.) Relay contacts
Pulsed DC Trigger Output Wiring
The pulsed DC Trigger output delivers 0VDC to 29VDC (approx.) from terminals 8
(positive) and 9 (negative).
Analog (4 to 20mA) Output Wiring
The 4 to 20mADC output is available on terminals 8 (positive) and 9 (negative). For
proper operation of the analog output, set parameter Ct (in 3
Alarm Relay Output
The Alarm Relay is a normally open (N.O.) switch available at terminals 4 and 5. Relays
themselves do NOT supply power, power must be supplied; wire the relay as shown in
the diagram.
External
Power
Source
Normally Open (N.O.) Relay contacts
External
Power
Source
Normally Closed (N.C.) relay contacts
Control Output Wiring
Alarm Device
i.e., buzzer, indicator,
siren, cut-off switch,
etc.
4 5
Alarm Output Wiring
9 Model 48VTR - Version 5.0 – January 2006
Control Device
i.e., Heater, Valve,
Pump, Switch, etc.
8
10
rd
Menu Level) to '0'.