Emerson 755A manual 26

Instruction Manual

245364-V May 2002

Model 755A

A. Typical ALARM 1 Setting

		40
		INPUT SIGNAL
	DEADBAND SET FOR
	20% OF FULLSCALE	Percent of Fullscale 30
		20
B. Typical ALARM 2 Setting
		55
		INPUT SIGNAL
	DEADBAND SET FOR
	10% OF FULLSCALE	Percent of Fullscale 50
		45

When input signal moves upscale through this point, the coil of ALARM 1 relay (K1) is energized, providing continuity between the common and normally-closed contacts of the relay.

ALARM 1 Setpoint

When input signal moves downscale through this point, the coil of ALARM 1 relay (K1) is de-energized, providing continuity between the common and normally-open contacts of the relay.

When input signal moves upscale through this point, the coil of ALARM 2 relay (K2) is de-energized, providing continuity between the common and normally-open contacts of the relay.

ALARM 2 Setpoint

When input signal moves upscale through this point, the coil of ALARM 2 relay (K2) is energized, providing continuity between the common and normally-closed contacts of the relay.

Figure 2-5. Typical Alarm Settings

REQUIREMENT	TYPICAL CONNECTIONS
	No. 1	NO		N
		COM		H
		NC	Alarm Bell	115 VAC
	RESET		or Lamp
Low Alarm,
Fail-Safe		NO
		COM
		NC
	RESET
	No. 2
	No. 1	NO
		COM
		NC
High Alarm,	RESET
Fail-Safe		NO		N
		COM
				H
		NC	Alarm Bell	115 VAC
	RESET		or Lamp
	No. 2
	No. 1	NO
		COM
		NC
Low Control	RESET		Solenoid
Limit,
		NO	Valve
Fail-Safe
		COM		H
		NC		N
	RESET			115 VAC
	No. 2

REQUIREMENT	TYPICAL CONNECTIONS
			Solenoid
	No. 1	NO	Valve
		COM		H
		NC		N
	RESET			115 VAC
Low Control
Limit,		NO
Fail-Safe
		COM
		NC
	RESET
	No. 2
Lower	No. 1	NO		N
		COM
Low Alarm				H
Indicator,		NC	Alarm Bell	115 VAC
Fail-Safe	RESET		or Lamp
			Solenoid
		NO	Valve
Low Control,		COM		H
		NC		N
Fail-Safe	RESET			115 VAC
	No. 2
			Solenoid
	No. 1	NO	Valve
High Control,		COM		H
Fail-Safe		NC
				N
	RESET			115 VAC
Higher		NO		N
		COM		H
High Alarm
		NC	Alarm Bell	115 VAC
Indicator,
			or Lamp
Fail-Safe	RESET
	No. 2

Figure 2-6. Relay Terminal Connections for Typical Fail-Safe Application

2-6 Installation Rosemount Analytical Inc. A Division of Emerson Process Management