Bosch Appliances D2071A manual Earth Ground Wiring, Zone 1, Alarm Initiating Circuit

D2071A Operations & Installation Guide 2.0 Installation

2.1Earth Ground Wiring

Only use Terminal 3, not telephone or electrical ground, for earth ground connections.

2.1.112 VAC Mode

To prevent damage from electrostatic charges or other transient electrical surges, use 16 AWG (1.5 mm) wire to connect the D2071A to earth ground at Terminal 3 before making other connections to the control panel. A grounding rod or cold water pipe are good earth ground references.

To determine the circuit’s electrical condition:

1.Ensure the D2071A is powered up and the loops are in a normal condition.

2.Use a multimeter to measure the voltage across the terminal connections. Connect one lead of the multimeter to a negative (-) terminal (6 or 7). Connect the other lead to a positive (+) terminal (8 or 9).

The measured zone input voltage reading for the electrical condition multimeter is Normal when Terminals 7 and 8 equal 1.0 VDC to 1.9 VDC, and Alarm (shorted) when Terminals 7 and 8 equal 0.0 VDC to 0.3 VDC.

2.1.2 24 VDC Mode 2.2.2 Retard and Reset Times

When the D2071A is connected to an FACP 24 VDC output, do not connect Terminal 3 to earth ground. This might cause a continuous ground fault condition on the FACP.

2.2Zone 1, Alarm Initiating Circuit

Use Terminals 6, 7, 8, and 9 for Zone 1 alarm initiating circuit connections.

Zone 1 is a four-wire, Class “A” initiating circuit. You can connect up to five waterflow alarm switches or up to 100 mechanically operated devices such as heat detectors or manual pull stations to this zone. NFPA 72 requires you to connect a single pull station with waterflow switches. The AHJ might specify the location of this pull station. Other than this exception, do not combine waterflow switches with other types of devices.

Unlike the two-wire Class “B” circuits supervised by EOL resistors, the double loop Class “A” circuit provides alarm response from all initiating devices with a single open or ground fault condition on the circuit. Connect the initiating devices to the D2071A as shown in Figure 2 on page 8 and Figure 3 on page 9.

The D2071A has programmable retard (retard time) and reset (reset time) timers for waterflow alarm installations on wet pipe sprinkler systems. These timers compensate for water pressure surges and sprinkler alarm valve fanning conditions.

2.2.1Class “A” Circuit Parameters

The maximum resistance on the Class “A” circuit sensor loop wiring is 100 Ω per loop (between A1 and A2

100 Ω maximum, between B1 and B2 100 Ω maximum).

Only use the Zone 1 retard or reset feature for waterflow switches and controls without their own retard and reset features.

The retard timer prevents false alarms from conditions such as water supply surges in wet pipe sprinkler systems. These surges can occur during a brief activation of a waterflow alarm switch. The value you enter in Retard Time determines the length of time the waterflow switch remains activated before an Alarm Report is initiated. Generally, a 15-sec retard is adequate, but a longer interval might be necessary during extended surge conditions.

Reset Time is the parameter that compensates for sprinkler alarm valve fanning conditions in wet pipe systems with unique hydraulic problems. Fanning occurs when a sprinkler head activates or the inspector’s test valve opens and the waterflow switch does not activate long enough to overcome the retard time, but the waterflow switch cycles between alarm and normal conditions.

The retard and reset timers work together as follows:

•The retard timer tracks the time the alarm initiating circuit is in the alarm condition. It begins counting when the circuit enters the alarm condition.

•The reset timer determines when the retard timer resets to zero. When the alarm initiating circuit enters a non-alarm (restored or trouble) condition after being in the alarm condition, the retard timer stops at its current value and the reset timer begins counting.

•If another alarm condition is detected before the reset timer reaches the value entered in reset time, the retard timer resumes counting from where it stopped and the reset timer is set to zero.

1 0 Bosch 09/04 74-06200-000-F